The document discusses the development of charge exchange injection and production of circulating proton beams with intensities greater than the space charge limit. It summarizes early work at Novosibirsk INP in the 1960s-1970s on accumulating proton beams using charge exchange injection up to the space charge limit. It also describes observations of the electron-proton instability in coasting beams and methods for damping instabilities. Later work was able to produce proton beams with intensities up to 9 times above the space charge limit through compensation of the beam space charge by secondary electrons. Diagnostics such as residual gas ionization monitors were important for characterizing the circulating beams.
Surface Plasmon Hybridization of Whispering Gallery Mode Microdisk LaserOka Kurniawan
This document summarizes research on using a plasmonic microdisk laser to efficiently generate and couple surface plasmon polaritons. The microdisk laser exhibits high-intensity whispering gallery modes that are hybridized with surface plasmon modes by attaching metal layers. This creates a surface plasmon source with over 20,000 times electric field enhancement. Simulation shows 60% coupling efficiency between the plasmonic microdisk laser and an adjacent metal-insulator-metal waveguide to transport surface plasmon polaritons. The structure could enable both high-speed and miniaturized plasmonic devices and circuits.
Electrostatic Edge Plasma Turbulence in the Uragan-3M torsatronAleksey Beletskii
The document summarizes electrical probe measurements of electrostatic edge plasma turbulence in the Uragan-3M torsatron. Key findings include: (1) plasma density fluctuations in the scrape-off layer and divertor region exhibit a spectral splitting depending on position relative to the last closed magnetic surface; (2) formation of radial electric field shear decreases turbulence and anomalous transport at the plasma edge; (3) turbulence data from Uragan-3M is included in the International Stellarator/Heliotron Edge Turbulence Database. Future work involves direct measurements of plasma potential and electron temperature fluctuations using a new combined probe.
Magnon crystallization in kagomé antiferromagnetsRyutaro Okuma
This document summarizes research on magnon crystallization in kagomé antiferromagnets. Key points include:
1) Observation of a series of magnetization plateaus up to 160 T in CdK and a 1/3 magnetization plateau over 150 T in herbertsmithite.
2) Theoretical calculation showing hexagonal magnon localization and crystallization phases with different magnetization values as the field is increased.
3) Experimental studies of the S=1/2 kagomé magnets volborthite, herbertsmithite, and Cd-kapellasite using ultra-high magnetic fields up to 200 T to observe magnon crystallization phenomena.
The document describes an experiment where quantum state transfer was realized between atomic and photonic qubits. Efficiencies of 0.04 and 0.03 were measured for the read and write processes respectively. It is estimated that implementing a second node and joint detection of signal photons could realize quantum repeater protocols and distant teleportation of atomic qubits at a rate of around 3 x 10-7 s-1. Improvements to efficiency through increasing optical thickness or eliminating transmission losses could increase the rate by several orders of magnitude. The results also demonstrate the possibility of multiple atomic qubits in a quantum node using multiple light beams.
1. The document outlines research on organic spintronics conducted by Zeev Valy Vardeny and collaborators at the University of Utah.
2. A key finding was the first demonstration of an organic spin valve using ferromagnetic La0.7Sr0.3MnO3 and Co electrodes separated by the organic semiconductor Alq3, which showed a giant magnetoresistance of over 12%.
3. The research aims to exploit unique properties of organic semiconductors like weak spin-orbit coupling and long spin relaxation times for applications in spin injection and detection.
The document summarizes the research of Zeev Valy Vardeny and his collaborators on organic spintronics at the University of Utah. Some of their key findings include:
1) Demonstrating the first organic spin-valve device using LSMO/Alq3/Co layers, which showed a giant magnetoresistance of over 12%.
2) Studying spin dynamics and relaxation processes in organic semiconductors using spin-valve and Hanle effect measurements.
3) Exploring new device concepts like organic spin light-emitting diodes by injecting spin-polarized carriers into organic layers.
The document summarizes research on magnetism at oxide interfaces. It discusses how interfaces between complex oxide materials like LaAlO3 and SrTiO3 can exhibit emergent properties not present in the constituent materials, such as ferromagnetism. Experimental techniques like SQUID, torque magnetometry, and XMCD are used to study the magnetic behavior and determine its origin. Theoretical predictions and XAS data indicate the magnetism arises from a reconstructed dxy orbital state of interfacial Ti3+ ions enabled by symmetry breaking and electronic reconstruction at the interface. Potential device applications involving spin injection and field effect transistors are also presented.
Graphene plasmonic couple to metallic antennaxingangahu
1. The document proposes a novel nanoantenna configuration using a metallic dipole antenna on top of an insulator layer, with a graphene sheet attached below the insulator.
2. By modifying the chemical potential of the graphene sheet using an applied gate voltage, the dispersion relation and optical conductivity of graphene can be tuned.
3. This allows the in-phase and out-of-phase coupling between the metallic plasmonics and graphene plasmonics to modify characteristics of the metal-graphene nanoantenna like its resonance frequency, near-field and far-field responses.
Surface Plasmon Hybridization of Whispering Gallery Mode Microdisk LaserOka Kurniawan
This document summarizes research on using a plasmonic microdisk laser to efficiently generate and couple surface plasmon polaritons. The microdisk laser exhibits high-intensity whispering gallery modes that are hybridized with surface plasmon modes by attaching metal layers. This creates a surface plasmon source with over 20,000 times electric field enhancement. Simulation shows 60% coupling efficiency between the plasmonic microdisk laser and an adjacent metal-insulator-metal waveguide to transport surface plasmon polaritons. The structure could enable both high-speed and miniaturized plasmonic devices and circuits.
Electrostatic Edge Plasma Turbulence in the Uragan-3M torsatronAleksey Beletskii
The document summarizes electrical probe measurements of electrostatic edge plasma turbulence in the Uragan-3M torsatron. Key findings include: (1) plasma density fluctuations in the scrape-off layer and divertor region exhibit a spectral splitting depending on position relative to the last closed magnetic surface; (2) formation of radial electric field shear decreases turbulence and anomalous transport at the plasma edge; (3) turbulence data from Uragan-3M is included in the International Stellarator/Heliotron Edge Turbulence Database. Future work involves direct measurements of plasma potential and electron temperature fluctuations using a new combined probe.
Magnon crystallization in kagomé antiferromagnetsRyutaro Okuma
This document summarizes research on magnon crystallization in kagomé antiferromagnets. Key points include:
1) Observation of a series of magnetization plateaus up to 160 T in CdK and a 1/3 magnetization plateau over 150 T in herbertsmithite.
2) Theoretical calculation showing hexagonal magnon localization and crystallization phases with different magnetization values as the field is increased.
3) Experimental studies of the S=1/2 kagomé magnets volborthite, herbertsmithite, and Cd-kapellasite using ultra-high magnetic fields up to 200 T to observe magnon crystallization phenomena.
The document describes an experiment where quantum state transfer was realized between atomic and photonic qubits. Efficiencies of 0.04 and 0.03 were measured for the read and write processes respectively. It is estimated that implementing a second node and joint detection of signal photons could realize quantum repeater protocols and distant teleportation of atomic qubits at a rate of around 3 x 10-7 s-1. Improvements to efficiency through increasing optical thickness or eliminating transmission losses could increase the rate by several orders of magnitude. The results also demonstrate the possibility of multiple atomic qubits in a quantum node using multiple light beams.
1. The document outlines research on organic spintronics conducted by Zeev Valy Vardeny and collaborators at the University of Utah.
2. A key finding was the first demonstration of an organic spin valve using ferromagnetic La0.7Sr0.3MnO3 and Co electrodes separated by the organic semiconductor Alq3, which showed a giant magnetoresistance of over 12%.
3. The research aims to exploit unique properties of organic semiconductors like weak spin-orbit coupling and long spin relaxation times for applications in spin injection and detection.
The document summarizes the research of Zeev Valy Vardeny and his collaborators on organic spintronics at the University of Utah. Some of their key findings include:
1) Demonstrating the first organic spin-valve device using LSMO/Alq3/Co layers, which showed a giant magnetoresistance of over 12%.
2) Studying spin dynamics and relaxation processes in organic semiconductors using spin-valve and Hanle effect measurements.
3) Exploring new device concepts like organic spin light-emitting diodes by injecting spin-polarized carriers into organic layers.
The document summarizes research on magnetism at oxide interfaces. It discusses how interfaces between complex oxide materials like LaAlO3 and SrTiO3 can exhibit emergent properties not present in the constituent materials, such as ferromagnetism. Experimental techniques like SQUID, torque magnetometry, and XMCD are used to study the magnetic behavior and determine its origin. Theoretical predictions and XAS data indicate the magnetism arises from a reconstructed dxy orbital state of interfacial Ti3+ ions enabled by symmetry breaking and electronic reconstruction at the interface. Potential device applications involving spin injection and field effect transistors are also presented.
Graphene plasmonic couple to metallic antennaxingangahu
1. The document proposes a novel nanoantenna configuration using a metallic dipole antenna on top of an insulator layer, with a graphene sheet attached below the insulator.
2. By modifying the chemical potential of the graphene sheet using an applied gate voltage, the dispersion relation and optical conductivity of graphene can be tuned.
3. This allows the in-phase and out-of-phase coupling between the metallic plasmonics and graphene plasmonics to modify characteristics of the metal-graphene nanoantenna like its resonance frequency, near-field and far-field responses.
The public trial lecture presented by Mohammadreza Nematollahi on 8th of October 2014 at Norwegian University of Science and Technology. The theoretical models and the experimental progress of highly mismatched alloys, as well as their optoelectronic applications are covered.
This document summarizes research on amphiphiles and Langmuir monolayers. It discusses how amphiphiles are composed of a hydrophilic head and hydrophobic tail. When spread on water, amphiphiles form Langmuir monolayers where the heads interact with water and tails with air. Pressure-area isotherms of these monolayers show phase transitions as pressure increases. Adding metal ions to the water subphase can induce superlattice formation underneath the monolayer. Studies using x-ray diffraction and other techniques characterized the structures of various Langmuir monolayers and how they change with conditions like subphase pH and metal ion type.
Ion beam irradiation of polycarbonate_TESTMircea Chipara
Ion beam irradiation was used to study the effects on polycarbonate polymers. Ion beams can excite atoms and molecules, generate phonons and heat samples. This can lead to breaking of chemical bonds, ionizations, and formation of radicals and defects. Radicals generated by ion beams can cause macromolecular chain scission or crosslinking. Spectroscopic analysis using ESR, UV-VIS and luminescence revealed that ion beam irradiation generates free radicals along particle tracks coupled by exchange interactions. The concentration of free radicals and deposited dose depends on penetration depth and linear energy transfer.
The document describes a time-of-flight mass spectrometer prototype called the Neutral and Ion Mass spectrometer (NIM) that was developed for the JUICE (Jupiter Icy Moon Explorer) space mission. Test results are presented for the NIM's two modes: neutral mode, which analyzes neutral gas particles, and ion mode, which analyzes ionized particles. The tests involved analyzing neon gas mixtures to assess the instrument's precision in determining isotope abundances, with the neutral mode achieving sub-0.1% accuracy and the ion mode unable to be tested due to instrumentation issues.
Nuclear chemistry deals with radioactive processes and nuclear properties. It includes the study of radioactive sources and their applications. Nuclear chemistry examines the nucleus, nuclear changes, particles within the nucleus, and radiation emission or absorption. Radioactive decay occurs naturally in heavy elements and can be artificially induced by bombarding stable nuclei with particles. There are several types of radioactive emissions including alpha, beta, gamma rays, and positron decay. Nuclear chemistry has many applications in medicine such as cancer treatment, sterilization, and tracing blood flow. It is also used in agriculture to improve crops and control pests.
Adding quantum wells to the intrinsic region of a p-i-n solar cell improves its conversion efficiency in the following ways:
1. Quantum wells allow a wider range of photon energies to be absorbed by shifting electrons to higher energy levels. This improves the solar spectrum absorption.
2. Electron-hole pairs generated in the quantum wells have a longer lifetime, increasing the probability that they will separate and be collected before recombining.
3. The quantum wells act as intermediate energy levels, allowing photons of lower energy to still promote electrons provided the energy difference is matched by the quantum well transition.
However, limitations include the solar spectrum not being truly monochromatic, so not all energies can be utilized.
The document summarizes a proposal for a new neutron electric dipole moment (EDM) experiment at the Spallation Neutron Source (SNS). The experiment aims to improve the current neutron EDM sensitivity by two orders of magnitude using ultra-cold neutrons produced in superfluid helium-4 and polarized helium-3 as a co-magnetometer. Many feasibility studies have been conducted, including tests of the helium-3 spin precession frequency matching technique. Construction of the new neutron EDM experiment is expected to begin in fiscal year 2010 with the goal of reaching a sensitivity of less than 1×10-28 e-cm.
This document summarizes a study that measured the binding energy of negative gallium ions using infrared photodetachment threshold spectroscopy. The experiment involved generating gallium ions using a cesium sputter source, mass selecting them with a magnetic field, and scanning a tunable laser across photon energy thresholds to photodetach electrons. Precise measurements of three photodetachment thresholds were obtained and agreed with theoretical values but revised a previous experimental measurement. A simulation of the experimental data using Wigner's threshold law for photodetachment cross sections also showed good agreement.
Dr. Mitat A. Birkan presents an overview of his program, Space Propulsion and Power, at the AFOSR 2013 Spring Review. At this review, Program Officers from AFOSR Technical Divisions will present briefings that highlight basic research programs beneficial to the Air Force.
the paper focuses on the fabrication and characterization of heterostructures using transition metal dichalcogenide (TMDC) monolayers. The authors describe the process of mechanical exfoliation to obtain thin flakes of TMDC material, which are then placed on a viscoelastic polydimethylsiloxane film. These monolayers are subsequently stamped onto a silicon wafer covered with thermal oxide to create heterobilayers .
The paper also discusses the use of ultrafast optical-pump/terahertz-probe near-field microscopy to study these heterostructures. The authors explain that this technique allows them to investigate the electric near fields and scattered fields of the emitted waveforms, as well as the photo-induced polarizability .
The experimental setup involves a high-average-power, low-noise Yb:YAG thin-disc oscillator, which generates terahertz probe pulses through optical rectification of 200-fs-long pulses. These pulses are centered at a wavelength of 1,030 nm and are generated in a gallium phosphide crystal .
The paper likely includes additional details on the experimental procedures, data analysis, and results obtained from the terahertz near-field microscopy experiments. It may also discuss the potential applications and implications of the findings
Complete description of piezoelectric sensors along with diagrams for better understanding. It is beneficial for any college student who is making a project or presentation on piezoelectric sensors. For presentation on this topic please drop by my uploaded presentations.
Dr. Toma Susi (University of Vienna, Austria) invited talk at the MRS Spring Meeting 2018 in Phoenix, AZ titled "Towards atomically precise manipulation of 2D nanostructures in the
electron microscope".
international workshop accelerator based neutron sources for medical industrial and scientific applications torino eurosea international workshop accelerator based neutron sources for medical industrial and scientific applications torino eurosea
This document provides an introduction to the thesis which focuses on aspects of symmetry, disorder and the Josephson effect in d-wave superconductors. Some key points:
- The thesis studies d-wave superconductors where the gap function changes sign in certain crystal directions, in contrast to conventional s-wave superconductors where the gap is isotropic.
- For a disordered d-wave superconductor, numerical, perturbative and field theoretical methods are used to calculate the density of states, finding it follows a sublinear power law at low energies.
- The Josephson effect in d-wave superconductors is investigated using a tunneling Hamiltonian approach to understand experiments on bicrystal junctions
This document summarizes research on using the enhanced electric field generated by surface plasmons on gold nanoparticles to non-resonantly excite photochromic molecules. The researchers coated gold nanospheres with a photochromic molecule called DAE1 and showed that 800nm light, which does not normally convert DAE1, was able to do so in the presence of the nanoparticles. They varied experimental conditions like nanoparticle size and structure. Images were also taken of plasmonic antennas made of nanorods that generate even stronger electric fields and could potentially induce conversion at even longer wavelengths than 800nm.
Atomic Plane Resolution Electron Magnetic Circular DichroismRiccardo Di Stefano
The document provides an overview of magnetic measurements using atomic-plane resolution electron magnetic circular dichroism (APR-EMCD). APR-EMCD allows for magnetic measurements with atomic resolution by using a convergent atomic-sized electron probe in a three-beam condition. In a single acquisition, APR-EMCD can obtain an annular dark field image, thickness information, and left and right circularly polarized EELS spectra to measure the EMCD effect without needing to modify conventional STEM microscopes. Experiments on 30nm thin Fe samples demonstrated the localization of the APR-EMCD signal at positions ±d/4 from lattice planes in agreement with simulations. Data analysis using canonical polyadic decomposition helped identify the magnetic
Nuclear magnetic resonance by ayush kumawatAyush Kumawat
This document provides an overview of a presentation on Nuclear Magnetic Resonance (NMR) Spectroscopy. The presentation covers the history of NMR, principles, instrumentation, techniques and applications of NMR spectroscopy. It discusses key topics such as NMR spectra, spin quantum number, chemical shift, spin-spin coupling and solvents used. The presentation was given by Ayush Kumawat, a 7th semester B.Pharma student under the guidance of Dr. Priyadarshini Kamble at BHUPAL NOBEL’S COLLEGE OF PHARMACY in Udaipur.
Modeling the Dependence of Power Diode on Temperature and RadiationIJPEDS-IAES
A theoretical study had been carried out on the effect of radiation on the
electrical properties of silicon power diodes. Computer program
"PDRAD2015" was developed to solve the diode equations and to
introduce the operating conditions and radiation effects upon its
parameters. Temperature increase interrupts the electrical properties of the
diode in the direction of drop voltage decrease across the p-n junction. The
model was analyzed under the influence of different radiation type (gammarays,
neutrons, protons and electrons) with various dose levels and
energies. The carrier’s diffusion lengths were seriously affected leading
to a large increase in the forward voltage. These effects were found to be
function of radiation type, fluence and energy.
This document provides information about swift heavy ion irradiation and its role in materials science. It discusses the 15UD Pelletron facility at Inter University Accelerator Centre in New Delhi, India, which can produce beams of various heavy ions up to 15MV. Energetic heavy ions can modify materials through electronic and nuclear energy loss. Defect formation, amorphization, and phase transformations can occur in materials due to swift heavy ion irradiation. The document focuses on using this technique to study and modify properties of nonlinear optical materials for applications in photonics and optoelectronics.
Analysis of Pseudogap in SuperconductorsIOSR Journals
The document analyzes the effect of the pseudogap on the static magnetic susceptibility of the high-temperature superconductor YBa2Cu3O7-δ. Magnetic susceptibility measurements were taken for various levels of oxygen deficiency δ, corresponding to different hole concentrations p. The data shows anomalous suppression of magnetic susceptibility above the critical temperature Tc in the underdoped region, indicative of the presence of a pseudogap. Analysis of the temperature and doping dependence of the magnetic susceptibility provides information about the pseudogap energy scale and its variation with hole concentration p.
The public trial lecture presented by Mohammadreza Nematollahi on 8th of October 2014 at Norwegian University of Science and Technology. The theoretical models and the experimental progress of highly mismatched alloys, as well as their optoelectronic applications are covered.
This document summarizes research on amphiphiles and Langmuir monolayers. It discusses how amphiphiles are composed of a hydrophilic head and hydrophobic tail. When spread on water, amphiphiles form Langmuir monolayers where the heads interact with water and tails with air. Pressure-area isotherms of these monolayers show phase transitions as pressure increases. Adding metal ions to the water subphase can induce superlattice formation underneath the monolayer. Studies using x-ray diffraction and other techniques characterized the structures of various Langmuir monolayers and how they change with conditions like subphase pH and metal ion type.
Ion beam irradiation of polycarbonate_TESTMircea Chipara
Ion beam irradiation was used to study the effects on polycarbonate polymers. Ion beams can excite atoms and molecules, generate phonons and heat samples. This can lead to breaking of chemical bonds, ionizations, and formation of radicals and defects. Radicals generated by ion beams can cause macromolecular chain scission or crosslinking. Spectroscopic analysis using ESR, UV-VIS and luminescence revealed that ion beam irradiation generates free radicals along particle tracks coupled by exchange interactions. The concentration of free radicals and deposited dose depends on penetration depth and linear energy transfer.
The document describes a time-of-flight mass spectrometer prototype called the Neutral and Ion Mass spectrometer (NIM) that was developed for the JUICE (Jupiter Icy Moon Explorer) space mission. Test results are presented for the NIM's two modes: neutral mode, which analyzes neutral gas particles, and ion mode, which analyzes ionized particles. The tests involved analyzing neon gas mixtures to assess the instrument's precision in determining isotope abundances, with the neutral mode achieving sub-0.1% accuracy and the ion mode unable to be tested due to instrumentation issues.
Nuclear chemistry deals with radioactive processes and nuclear properties. It includes the study of radioactive sources and their applications. Nuclear chemistry examines the nucleus, nuclear changes, particles within the nucleus, and radiation emission or absorption. Radioactive decay occurs naturally in heavy elements and can be artificially induced by bombarding stable nuclei with particles. There are several types of radioactive emissions including alpha, beta, gamma rays, and positron decay. Nuclear chemistry has many applications in medicine such as cancer treatment, sterilization, and tracing blood flow. It is also used in agriculture to improve crops and control pests.
Adding quantum wells to the intrinsic region of a p-i-n solar cell improves its conversion efficiency in the following ways:
1. Quantum wells allow a wider range of photon energies to be absorbed by shifting electrons to higher energy levels. This improves the solar spectrum absorption.
2. Electron-hole pairs generated in the quantum wells have a longer lifetime, increasing the probability that they will separate and be collected before recombining.
3. The quantum wells act as intermediate energy levels, allowing photons of lower energy to still promote electrons provided the energy difference is matched by the quantum well transition.
However, limitations include the solar spectrum not being truly monochromatic, so not all energies can be utilized.
The document summarizes a proposal for a new neutron electric dipole moment (EDM) experiment at the Spallation Neutron Source (SNS). The experiment aims to improve the current neutron EDM sensitivity by two orders of magnitude using ultra-cold neutrons produced in superfluid helium-4 and polarized helium-3 as a co-magnetometer. Many feasibility studies have been conducted, including tests of the helium-3 spin precession frequency matching technique. Construction of the new neutron EDM experiment is expected to begin in fiscal year 2010 with the goal of reaching a sensitivity of less than 1×10-28 e-cm.
This document summarizes a study that measured the binding energy of negative gallium ions using infrared photodetachment threshold spectroscopy. The experiment involved generating gallium ions using a cesium sputter source, mass selecting them with a magnetic field, and scanning a tunable laser across photon energy thresholds to photodetach electrons. Precise measurements of three photodetachment thresholds were obtained and agreed with theoretical values but revised a previous experimental measurement. A simulation of the experimental data using Wigner's threshold law for photodetachment cross sections also showed good agreement.
Dr. Mitat A. Birkan presents an overview of his program, Space Propulsion and Power, at the AFOSR 2013 Spring Review. At this review, Program Officers from AFOSR Technical Divisions will present briefings that highlight basic research programs beneficial to the Air Force.
the paper focuses on the fabrication and characterization of heterostructures using transition metal dichalcogenide (TMDC) monolayers. The authors describe the process of mechanical exfoliation to obtain thin flakes of TMDC material, which are then placed on a viscoelastic polydimethylsiloxane film. These monolayers are subsequently stamped onto a silicon wafer covered with thermal oxide to create heterobilayers .
The paper also discusses the use of ultrafast optical-pump/terahertz-probe near-field microscopy to study these heterostructures. The authors explain that this technique allows them to investigate the electric near fields and scattered fields of the emitted waveforms, as well as the photo-induced polarizability .
The experimental setup involves a high-average-power, low-noise Yb:YAG thin-disc oscillator, which generates terahertz probe pulses through optical rectification of 200-fs-long pulses. These pulses are centered at a wavelength of 1,030 nm and are generated in a gallium phosphide crystal .
The paper likely includes additional details on the experimental procedures, data analysis, and results obtained from the terahertz near-field microscopy experiments. It may also discuss the potential applications and implications of the findings
Complete description of piezoelectric sensors along with diagrams for better understanding. It is beneficial for any college student who is making a project or presentation on piezoelectric sensors. For presentation on this topic please drop by my uploaded presentations.
Dr. Toma Susi (University of Vienna, Austria) invited talk at the MRS Spring Meeting 2018 in Phoenix, AZ titled "Towards atomically precise manipulation of 2D nanostructures in the
electron microscope".
international workshop accelerator based neutron sources for medical industrial and scientific applications torino eurosea international workshop accelerator based neutron sources for medical industrial and scientific applications torino eurosea
This document provides an introduction to the thesis which focuses on aspects of symmetry, disorder and the Josephson effect in d-wave superconductors. Some key points:
- The thesis studies d-wave superconductors where the gap function changes sign in certain crystal directions, in contrast to conventional s-wave superconductors where the gap is isotropic.
- For a disordered d-wave superconductor, numerical, perturbative and field theoretical methods are used to calculate the density of states, finding it follows a sublinear power law at low energies.
- The Josephson effect in d-wave superconductors is investigated using a tunneling Hamiltonian approach to understand experiments on bicrystal junctions
This document summarizes research on using the enhanced electric field generated by surface plasmons on gold nanoparticles to non-resonantly excite photochromic molecules. The researchers coated gold nanospheres with a photochromic molecule called DAE1 and showed that 800nm light, which does not normally convert DAE1, was able to do so in the presence of the nanoparticles. They varied experimental conditions like nanoparticle size and structure. Images were also taken of plasmonic antennas made of nanorods that generate even stronger electric fields and could potentially induce conversion at even longer wavelengths than 800nm.
Atomic Plane Resolution Electron Magnetic Circular DichroismRiccardo Di Stefano
The document provides an overview of magnetic measurements using atomic-plane resolution electron magnetic circular dichroism (APR-EMCD). APR-EMCD allows for magnetic measurements with atomic resolution by using a convergent atomic-sized electron probe in a three-beam condition. In a single acquisition, APR-EMCD can obtain an annular dark field image, thickness information, and left and right circularly polarized EELS spectra to measure the EMCD effect without needing to modify conventional STEM microscopes. Experiments on 30nm thin Fe samples demonstrated the localization of the APR-EMCD signal at positions ±d/4 from lattice planes in agreement with simulations. Data analysis using canonical polyadic decomposition helped identify the magnetic
Nuclear magnetic resonance by ayush kumawatAyush Kumawat
This document provides an overview of a presentation on Nuclear Magnetic Resonance (NMR) Spectroscopy. The presentation covers the history of NMR, principles, instrumentation, techniques and applications of NMR spectroscopy. It discusses key topics such as NMR spectra, spin quantum number, chemical shift, spin-spin coupling and solvents used. The presentation was given by Ayush Kumawat, a 7th semester B.Pharma student under the guidance of Dr. Priyadarshini Kamble at BHUPAL NOBEL’S COLLEGE OF PHARMACY in Udaipur.
Modeling the Dependence of Power Diode on Temperature and RadiationIJPEDS-IAES
A theoretical study had been carried out on the effect of radiation on the
electrical properties of silicon power diodes. Computer program
"PDRAD2015" was developed to solve the diode equations and to
introduce the operating conditions and radiation effects upon its
parameters. Temperature increase interrupts the electrical properties of the
diode in the direction of drop voltage decrease across the p-n junction. The
model was analyzed under the influence of different radiation type (gammarays,
neutrons, protons and electrons) with various dose levels and
energies. The carrier’s diffusion lengths were seriously affected leading
to a large increase in the forward voltage. These effects were found to be
function of radiation type, fluence and energy.
This document provides information about swift heavy ion irradiation and its role in materials science. It discusses the 15UD Pelletron facility at Inter University Accelerator Centre in New Delhi, India, which can produce beams of various heavy ions up to 15MV. Energetic heavy ions can modify materials through electronic and nuclear energy loss. Defect formation, amorphization, and phase transformations can occur in materials due to swift heavy ion irradiation. The document focuses on using this technique to study and modify properties of nonlinear optical materials for applications in photonics and optoelectronics.
Analysis of Pseudogap in SuperconductorsIOSR Journals
The document analyzes the effect of the pseudogap on the static magnetic susceptibility of the high-temperature superconductor YBa2Cu3O7-δ. Magnetic susceptibility measurements were taken for various levels of oxygen deficiency δ, corresponding to different hole concentrations p. The data shows anomalous suppression of magnetic susceptibility above the critical temperature Tc in the underdoped region, indicative of the presence of a pseudogap. Analysis of the temperature and doping dependence of the magnetic susceptibility provides information about the pseudogap energy scale and its variation with hole concentration p.
Travis Hills of MN is Making Clean Water Accessible to All Through High Flux ...Travis Hills MN
By harnessing the power of High Flux Vacuum Membrane Distillation, Travis Hills from MN envisions a future where clean and safe drinking water is accessible to all, regardless of geographical location or economic status.
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
Sexuality - Issues, Attitude and Behaviour - Applied Social Psychology - Psyc...PsychoTech Services
A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
PPT on Alternate Wetting and Drying presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdfSelcen Ozturkcan
Ozturkcan, S., Berndt, A., & Angelakis, A. (2024). Mending clothing to support sustainable fashion. Presented at the 31st Annual Conference by the Consortium for International Marketing Research (CIMaR), 10-13 Jun 2024, University of Gävle, Sweden.
CLASS 12th CHEMISTRY SOLID STATE ppt (Animated)eitps1506
Description:
Dive into the fascinating realm of solid-state physics with our meticulously crafted online PowerPoint presentation. This immersive educational resource offers a comprehensive exploration of the fundamental concepts, theories, and applications within the realm of solid-state physics.
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2. Motivation
For observation and damping of e-p and
ion-beam instability it is important to use
adequate diagnostics
For verification of computer codes for instability
simulation it is important to have a reliable experimental
date in simple conditions.
Experiments in small scale low energy rings can be used
for quantitative verification of simulation codes and for
development of methods for instability damping .
Informative diagnostics is important for collection of
necessary information.
3. Outline
e-p instability: historical remarks and references
Small scale Proton Storage Rings
Diagnostics
Observations
Damping of e-p instability
Production of a stable space charge compensated
circulating beam with high intensity
4. Abstract
Diagnostics for observation, identification and damping of instabilities driven
by interaction with secondary plasma in storage rings and synchrotrons will
be considered.
Clearing electrodes, fast gauges, fast valves, fast extractors, repulsing
electrodes, electron and ion collectors with retarding grids, particle
spectrometers used for the detection of secondary particle generation and
secondary particle identification will be discussed.
Features of electrostatic and magnetic dipole and quadrupole pickups will
be presented.
The influence of nonlinear generation of secondary plasma in driving and
stabilization of e-p instability will be discussed.
Observations of anomaly in secondary particle generation will be presented.
Conditions for accumulation of proton beam with intensity greater than
space charge limit will be discussed.
5. Two-stream instability, historical remarks
Beam instability due to compensating particles were
first observed with coasting proton beam and long proton
bunches at the Novosibirsk INP(1965), the CERN
ISR(1971), and the Los Alamos PSR(1986)…
Recently two-stream instability was observed in almost
all storage rings with high beam intensity.
Observation of two-stream instability in different
conditions will be reviewed.
Diagnostics and damping of two-stream instability will be
discussed.
6. Two-stream instability
Beam interaction with elements of accelerator and secondary
plasma can be the reason for instabilities, causing limited beam
performance.
Improving of vacuum chamber design and reducing of impedance by
orders of magnitude relative with earlier accelerators increases
threshold intensity for impedance instability.
Two-stream effects (beam interaction with a secondary plasma)
become a new limitation on the beam intensity and brightness.
Electron and Antiproton beams are perturbed by accumulated
positive ions.
Proton and positron beams may be affected by electrons or negative
ions generated by the beam. These secondary particles can induce
very fast and strong instabilities.
These instabilities become more severe in accelerators and storage
rings operating with high current and small bunch spacing.
7. This instability is a problem for heavy ion inertial fusion,
but ion beam with higher current density can be more
stable.
Instability can be a reason of fast pressure rise include electron
stimulated gas desorbtion, ion desorbtion, and beam loss/halo
scraping. Beam induced pressure rise had limited beam
intensity in CERN ISR and LEAR. Currently, it is a limiting
factor in RHIC, AGS Booster, and GSI SIS. It is a relevant
issue at SPS, LANL PSR, and B-factories. For projects under
construction and planning, such as SNS, LHC, LEIR, GSI
upgrade, and heavy ion inertial fusion, it is also of concern.
9. First project of proton/antiproton collider VAPP, in
the Novosibirsk INP (BINP), 1960
Development of charge-exchange injection (and
negative ion sources) for high brightness proton beam
production. First observation of e-p instability.
Development of Proton/ Antiproton converter.
Development of electron cooling for high brightness
antiproton beam production.
Production of space charge neutralized proton beam
with intensity above space charge limit. Inductance
Linac, Inertial Fusion, Neutron Generators.
10. History of Charge Exchange Injection
(Graham Rees, ISIS , ICFA Workshop)
1. 1951 Alvarez, LBL (H-) ;
1956 Moon, Birmingham Un. (H+2)
2. 1962-66 Budker, Dimov, Dudnikov, Novosibirsk ;
first achievements; discovery of e-p instability.IPM
3. 1968-70 Ron Martin, ANL ; 50 MeV injection at ZGS
4. 1972 Jim Simpson, ANL ; 50-200 MeV, 30 Hz booster
5. 1975-76 Ron Martin et al, ANL ; 6 1012 ppp
6. 1977 Rauchas et al, ANL ; IPNS 50-500 MeV, 30 Hz
7. 1978 Hojvat et al, FNAL ; 0.2-8 GeV, 15 Hz booster
8. 1982 Barton et al, BNL ; 0.2-29 GeV, AGS
9. 1984 First very high intensity rings ; PSR and ISIS
10. 1980,85,88 IHEP, KEK booster, DESY III (HERA)
11. 1985-90 EHF, AHF and KAON design studies. SSC
12. 1992 AGS 1.2 GeV booster injector
13. 1990's ESS, JHF and SNS 4-5 MW sources
11. History of
Surface Plasma Sources
Development
BDD, G.Budker, G.Dimov, V.Dudnikov
Charge-Exchange Injection
12. INP Novosibirsk, 1965, bunched beam
first observation of an e- driven instability?
coherent betatron oscillations & beam loss
with bunched proton beam; threshold ~1-1.5x1010,
circumference 2.5 m, stabilized by feedback
(G. Budker, G. Dimov, V. Dudnikov, 1965).
F. Zimmermann
Other INP PSR 1967:
coasting
beam instability
suppressed by
increasing beam
current;
fast accumulation of
secondary plasma
is essential for
stabilization;
1.8x1012 in 6 m
V. Dudnikov, PAC2001,
PAC2005
13. • Damped by extensive system of electrostatic clearing electrodes
ISR, coasting proton beam, ~1972
(R. Calder, E. Fischer, O. Grobner, E. Jones)
excitation of nonlinear
resonances; gradual
beam blow up similar
to multiple scattering
beam induced signal
from a pick up showing
coupled e-p oscillation;
beam current is 12 A and
beam energy 26 GeV
2x10-11 Torr,
3.5% neutralization,
DQ=0.015
14.
15.
16.
17.
18. PSR instability, 1988
(D. Neuffer et al, R. Macek et al.)
beam loss on time scale
of 10-100 ms above
threshold bunch charge
of 1.5x1013,
circumference 90 m,
transverse oscillations
at 100 MHz frequency
beam current and vertical oscillations;
hor. scale is 200 ms/div.
19. AGS Booster, 1998/99 (M.Blaskiewicz)
coasting beam
vertical instability
growth time ~3 ms
~100 MHz
downward shift as
instability progresses
beam current [A]
500 ms
-500 ms
5
y power density
0.2 GHz
time
20. KEKB e+ beam blow up, 2000 (H. Fukuma, et al.)
threshold of fast
vertical blow up
slow growth
below threshold?
beam current, mA
IP spot size
half of solenoids on
all solenoids off
all solenoids on
21. Vacuum pressure read-
out vs. total current as
recorded in four straight
section locations for the
electron (blue dots) and
positron (red dots) rings.
Evidence of electron cloud build-up in
DAFNE (PAC05, FPAP001,002)
22. Vacuum pressure
read-out vs. total
current as
recorded in 2
straight section of
the positron ring
where a
50 G solenoid field
was turned on (red
dots) and off
(blue dots).
Evidence of electron cloud build-up in
DAFNE (PAC05, FPAP001)
23. Electron cloud build-up
along two bunch trains
for the drift downstream
of the arc: a) simple drift,
b) drift with residual
magnetic field of By≈ .1 T,
c) drift with a 50
G solenoid. (Primary
electron rate dλe/ds=
0.26)
Simulation of electron cloud build-up in DAFNE
(PAC05, FPAP001)
24. Why no e-p Instability in the ISIS?
Exotic vacuum chamber? Defocusing,
scattering of secondary electrons? Collect
electrons as black body?
25. ISIS has much larger a and b, and low particle density. Bounce
frequency is low . Only low modes of betatron oscillations are
unstable. This lead to removing of electrons without beam loss.
28. References for first observation of e-p instability
V.Dudnikov, “The intense proton beam accumulation in storage ring by charge-
exchange injection method”, Ph.D.Thesis, Novosibirsk INP,1966.
G. Budker, G. Dimov, V. Dudnikov, “Experiments on production of intense proton
beam by charge exchange injection method” in Proceedings of International
Symposium on Electron and Positron Storage Ring, France,Sakley,1966, rep. VIII,
6.1 (1966).
G. Budker, G. Dimov, V. Dudnikov, “Experimental investigation of the intense proton
beam accumulation in storage ring by charge- exchange injection method”, Soviet
Atomic Energy, 22, 384 (1967).
G.Budker, G.Dimov, V. Dudnikov, V. Shamovsky, “Experiments on electron
compensation of proton beam in ring accelerator”, Proc.VI Intern. Conf. On High
energy accelerators, 1967, MIT & HU,A-104, CEAL-2000, (1967).
G.I.Dimov, V.G.Dudnikov,V.G.Shamovsky, ” Transverse instability of a proton beam
due to coherent interaction with a plasma in a circular accelerator” Soviet
Conference on Charge- particle accelerators”,Moscow,1968, translation from
Russian, 1 1973 108565 8.
G. Dimov, V. Dudnikov, V. Shamovsky, “Investigation of the secondary charged
particles influence on the proton beam dynamic in betatron mode ”, Soviet Atomic
Energy, 29,353 (1969).
Yu.Belchenko, G.Budker, G.Dimov, V.Dudnikov, et al. X PAC,1977.
O.Grobner, X PAC,1977.
E. Colton, D. Nuffer, G. Swain, R.Macek, et al., Particle Accelerators, 23,133
(1988).
29. Models of two-stream instability
The beam- induces electron cloud buildup and development of
two-stream e-p instability is one of major concern for all projects
with high beam intensity and brightness [1,2].
In the discussing models of e-p instability, transverse beam
oscillations is excited by relative coherent oscillation of beam
particles (protons, ions, electrons) and compensating particles
(electrons,ions) [3,4,5].
For instability a bounce frequency of electron’s oscillation in
potential of proton’s beam should be close to any mode of
betatron frequency of beam in the laboratory frame.
1. http://wwwslap.cern.ch/collective/electron-cloud/.
2. http://conference.kek.jp/two-stream/.
3. G.I.Budker, Sov.Atomic Energy, 5,9,(1956).
4. B.V. Chirikov, Sov.Atomic.Energy,19(3),239,(1965).
5. Koshkarev, Zenkevich, Particle Accelerators, (1971).
6. M.Giovannozzi, E.Metral, G.Metral, G.Rumolo,and F. Zimmerman , Phys.Rev.
ST-Accel. Beams,6,010101,(2003).
30. Memo from: Bruno Zotter
www.aps.anl.gov/conferences/icfa/twoo-stream/
Subject: Summary of my own conclusions of the
workshop
1) Go on with your plans to coat the most sensitive
locations in the PSR (Al stripper chamber, sections with
ceramics and with high losses) with Ti nitride - make
sure that the deposition technique avoids rapid flaking
off;
2) If this is not sufficiently successful, install a transverse
feedback system based on the wide-band split cylinder
pickups - Dudnikov showed an example where a simple
feedback seemed to work fine on e-p. If the oscillations
are kept sufficiently small by it, there may be no need for
high power;
31.
32. Development of Charge Exchange Injection and Production of
Circulating Beam with Intensity Greater than Space Charge Limit
V.Dudnikov. “Production of an intense proton beam in storage ring by a charge- exchange injection method”,
Novosibirsk, Ph.D.Thesis,INP, 1966.
Development of a Charge- Exchange Injection; Accumulation of proton beam up to space charge limit; Observation and damping of
synchrotron oscillation; Observation and damping of the coherent transverse instability of the bunched beam. Observation of the e-p
instability of coasting beam in storage ring.
G. Budker, G. Dimov, V. Dudnikov, “Experiments on production of intense proton beam by charge exchange injection method” in
Proceedings of International Symposium on Electron and Positron Storage Ring, France,Sakley,1966, rep. VIII, 6.1 (1966).
G. Budker, G. Dimov, V. Dudnikov, “Experimental investigation of the intense proton beam accumulation in storage ring by charge-
exchange injection method”, Soviet Atomic Energy, 22, 384 (1967).
G.Dimov, V.Dudnikov, “Determination of circulating proton current and current density distribution (residual gas ionization profile
monotor)”, Instrum. Experimental Techniques, 5, 15 (1967).
Dimov. “Charge- exchange injection of protons into accelerators and storage rings”, Novosibirsk, INP, 1968.
Development of a Charge- Exchange Injection; Accumulation of a proton beam up to the space charge limit; Observation and
damping of synchrotron oscillations; Observation and damping of the coherent transverse instability of the bunched beam;.
Shamovsky. “Investigation of the Interaction of the circulating proton beam with a residual gas”, Novosibirsk, INP, 1972.
Observation of transverse e-p coherent instability of the coasting beam in the storage ring, Observation of a transverse Herward’s
instability, Damping of instabilities, Accumulation of a proton beam with a space charge limit.
G. Dimov, V. Dudnikov, V. Shamovsky, “Transverse instability of the proton beam induced by coherent interaction with plasma in
cyclic accelerators”, Trudy Vsesousnogo soveschaniya po uskoritelyam, Moskva, 1968, v. 2, 258 (1969).
G. Dimov, V. Dudnikov, V. Shamovsky, “Investigation of the secondary charged particles influence on the proton beam dynamic in
betatron mode ”, Soviet Atomic Energy, 29,353 (1969).
G.Budker, G.Dimov, V. Dudnikov, V. Shamovsky, “Experiments on electron compensation of proton beam in ring accelerator”,
Proc.VI Intern. Conf. On High energy accelerators, 1967, MIT & HU,A-104, CEAL-2000, (1967).
Chupriyanov. “Production of intense compensated proton beam in an accelerating ring”, Novosibirsk, INP, 1982.
Observation and damping transverse coherent e-p instability of coasting proton beam and production of the proton beam with an
intensity up to 9.2 time above a space charge limit.
G.Dimov, V.Chupriyanov, “Compensated proton beam production in an accelerating ring at a current above the space charge limit”,
Particle accelerators, 14, 155- 184 (1984). Yu.Belchenko, G.Budker, G.Dimov, V.Dudnikov, et al.X PAC,1977.
33. General view of INP PSR
with charge exchange injection 1965
1. Magnet
2. Vacuum chamber
3. Beam line
5. First stripping target
6. Second stripping target
34. INP PSR for bunched beam accumulation by
charge exchange injection
1- fist stripper;
2- main stripper Pulsed
supersonic jet;
3- gas pumping;
4- pickup integral;
5- accelerating drift tube;
6- gas luminescent profile
Monitor;
7- Residual gas current
monitor;
8- residual gas IPM;
9- BPM;
10- transformer Current
monitor;
11- FC;
12- deflector for Suppression
transverse instability by
negative Feedback.
Small Radius- High beam density. Revolution 5.3 MHz. 1MeV, 0.5 mA, 1 ms.
35. PSR for Circulating p-Beam Production
1-striping gas target;
2-gas pulser;
3-FC;
4-Q screen;
5,6-moving targets;
7-ion collectors;
8-current monitor;
9-BPM;
10-Q pick ups;
11-magnetic BPM;
12-beam loss monitor;
13-detector of secondary particles
density;
14-inductor core;
15-gas pulsers;
16-gas leaks.
Proton Energy -1 MeV; injection-up to 8 mA; bending radius-42 cm; magnetic field-3.5 kG;index-
n=0.2-0.7; St. sections-106 cm;aperture-4x6 cm; revolution-1.86 MHz; circulating current up to
300mA is up to 9 time greater than a space charge limit.
36. Vacuum control
Stripping target- high dense supersonic hydrogen
jet (density up to e19 mol/cm3, target e17 mol/cm2 , ~1ms)
Vacuum e-5 Torr
Fast, open ion gauges
Fast compact gas valves, opening of 0.1 ms.
50. CERN Luminescence Profile Monitor
It works with N2 injection
1 light channel is going to a PM for
gas-luminescence studies (decay
time etc.)
2 channels are used for profile
measurements:
The H channel is in air: it showed
high background with LHC
beam, due to beam losses
The V channel is in vacuum
The MCP has a pre-programmed
variable gain over cycle
(it showed some problems to log on
timing events)
Beam
H & V Reference Screens
PM Tube
V profile MCP & CCD
H profile MCP & CCD
N2
injection
Filters
63. Transverse instability of bunched beam with a high
RF voltage
1-ring pickup, peak bunch
intensity ;
2-radial loss monitor.
Beam was deflected
after Instability loss.
Two peaks structure
of beam after
instability loss.
Only central part of
the beam was lost
64. Evolution of bunches profiles in INP PSR
1- 0.05 ms(100 turns);
2- 0.4 ms(1000 turns);
3- 0.8 ms (3000 turns);
4- 2.8 ms, before start
transverse instability.
Bunches period 188 ns
coasting beam injection
69. PSR for beam accumulation with inductive
acceleration
1-first stripper;
2-magnet pole n=0.6;
3-hollow copper torus
with inductance current;
4-main stripper;
5-accelerating gap;
6-ring pickup;
7-BPMs;
8-Res.gas IPM;
9-vacuum chamber.
FC; quartz screens;
Retarding electron and
ion collectors/
spectrometers .
70. e-p instability with a low threshold in INP PSR
1-beam current, N>7e9p
2-beam potential, slow
Accumulation of electrons
10mcs, and fast loss 1mcs.
3-retarding electron
collector;
4,5-ion collector, ionizing
Current Monitor;
6,7-ion Collectors Beam
potential monitor;
8,9- negative mass
Instability.
Injection:
Coasting beam, 1MeV,
0.1mA
R=42 cm.
71. Instability of coasting beam in AG PSR, 1967
1- beam current
monitor;
2- vertical proton
loss monitor;
3- radial proton loss;
4- detected signal of
vertical BPM.
20 mcs/div.
75. Small Scale Proton Storage Ring for Accumulation of
Proton Beam with Intensity Greater than
Space Charge Limit
76. Beam accumulation with clearing voltage
Secondary plasma
accumulation
suppressed by strong
transverse electric field.
Vertical instability with
zero mode oscillation
was observed
(Herward instability).
77. Threshold intensity N (left) and growth rate J (right) of
instability as function of gas density n
a- hydrogen; b- helium; c- air.
87. Build-up time due to ionization for the
instability
Ionization (2x10-7 Pa)
Y1,i=8x10-9e-/(m.p)
t= fth/cY1,i =0.4 fth
JPARC-MR 0.6ms
PSR 10 ms instability is observed
ISIS 180 ms no instability
AGS booster 60 ms instability
AGS 10 ms no instability
FNAL-MI 0.2 ms
KEK-PS 20 ms no instability
92. Observation of anomaly in secondary electron
generation in the FERMILAB Booster
Observation of secondary particles in the booster proton beam are presented in the
Booster E-Log at 04/06/01 .
Reflecting plate of the Vertical Ionization Profile Monitor (VIPM) was connected to the
1 MOhm input of oscilloscope (Channel 2).
To channel 1 is connected a signal of proton beam Charge monitor Qb, with
calibration of 2 E12 p/V.
Oscilloscope tracks of the proton beam intensity Qb (uper track) and current of
secondary particles (electrons) Qe (bottom track) are shown in Fig. 1 in time scale 5
ms/div (left) and 0.25 ms/ div (right).
The voltage on MCP plate is Vmcp=-200 V.
It was observed strong RF signal induced by proton beam with a gap ( one long
bunch). For intensity of proton beam Qb< 4E12 p electron current to the VIPM plate
is low ( Qe< 0.1 V~ 1E-7 A) as corresponded to electron production by residual gas
ionization by proton beam.
For higher proton beam intensity (Qb> 4E12p) the electron current to the VIPM plate
increase significantly up to Qe=15 V~ 15 E-6 A as shown in the bottom
oscillogramms. This current is much greater of electron current produced by simple
residual gas ionization. This observation present an evidence of formation of high
density of secondary particles in high intense proton beam in the booster, as in Los
Alamos PSR and other high intense rings.
Intense formation of secondary particles is important for the beam behavior and
should be taken into account in the computer simulation.
96. Cold emission of electrons from electrodes with dielectric films
CATHODE DEPOSITS INDUCE DISCHARGES: cold emission
POSITIVE IONS ACCUMULATION
CREATES HIGH DIPOLE FIELD, INDUCING
ELECTRON EXTRACTION (MALTER
EFFECT) or sparks
+ ++++++ +
- -
DEPOSITS
97. Instrumentation for observation and damping of
e-p instability
1. Observation of plasma (electrons) generation and correlation with an instability
development. Any insulated clearing electrodes could be used for detection of
sufficient increase of the electron density. More sophisticated diagnostics (from ANL)
is used for this application in the LANL PSR. These electrodes in different location
could be used for observation of distribution of the electron generation.
2. For determination an importance compensating particles it is possible to use a
controlled triggering a surface breakdown by high voltage pulse on the beam pipe
wall or initiation unipolar arc. Any high voltage feedthrough could be used for
triggering of controlled discharge. Could this break down initiate an instability?
3. For suppression of plasma production could be used an improving of surface
properties around the proton beam. Cleaning of the surface from a dust and
insulating films for decrease a probability of the arc discharge triggering. Deposition
of the films with a low secondary emission as TiN, NEG. Transparent mesh near the
wall could be used for decrease an efficient secondary electron emission and
suppression of the multipactor discharge. Biased electrodes could be used for
suppressing of the multipactor discharge, as in a high voltage RF cavity.
4. Diagnostics of the circulating beam oscillation by fast (magnetic) beam position
monitors (BPM).
5. Local beam loss monitor with fast time resolution. Fast scintillator, pin diodes.
6. Transverse beam instability is sensitive to the RF voltage. Increase of the RF
voltage is increase a delay time for instability development and smaller part of the
beam is involved in the unstable oscillation development.
7. Instability sensitive to sextuple and octupole component of magnetic field,
chromaticity (Landau Damping), …
98. Electron generation and suppression
Gas ionization by beam and by secondary electrons.
Photoemission excited by SR.
Secondary emission, RF multipactor,ion-electron emiss.
Cold emission; Malter effect; Unipolar arc discharge
(explosion emission). Artificial triggering of arc.
Suppression:
1-clearind electrodes; Ultra high vacuum.
Gaps between bunches.
Low SEY coating: TiN, NEG.
Transverse magnetic field.
Arc resistant material
99. Conclusion
Experimental dates from small scale rings can
be used for verification of computer simulation.
Stabilization of space charge compensated
proton beam with a high intensity has been
observed.
It is useful to use low energy proton ring for
investigation e-p instability.