Atmospheric Microwave Plasma Torches for Advanced Cleaning<br />Giovanni Terenziani<br />FabrizioStivanello<br />Antonio A...
Outline<br />Plasma Introduction<br /><ul><li>LTE or Non-LTE and Classification</li></ul>Our Configuration<br /><ul><li>Se...
Cleaning Experiments
Results</li></ul>Improvements<br /><ul><li>Vapor
Cut Off
Plasma Bending</li></ul>Final Considerations<br />
Plasma’s Pressure Regimes<br />PlasmasNon in Local Thermodynamic<br />Equilibrium (Non-LTE plasma)<br />Plasmas in Local T...
Electron density: 1021 – 1026 m-3
Inelastic collision create reactive species
(elastic one heat heavy particle)
 Te >> Th
 Electron density: <1019 m-3
Inelastic collision induce the plasma chemistry
 (elastic slightly raise heavy particle kinetic energy)</li></li></ul><li>Types of Atmospheric Plasmas<br />DC and low fre...
Types of Atmospheric Plasmas<br />DC and low frequency discharge<br />RF waves<br />Microwaves discharge<br />Industrial s...
Types of Atmospheric Plasmas<br />DC and low frequency discharge<br />RF waves<br />Microwaves discharge<br />Industrial s...
Semi Metallic Plasma Torch<br />
General Structure of a Plasma Torch<br /><ul><li>A microwave source (Amplifier, generator)
Microwave equipment (wave guide, tuning system, circulator)
 An ignition system
 A gas nozzle (a quartz tube with flowing gas)</li></li></ul><li>3-T Plasma rules<br />Plasma is ruled by 3 T-factors:<br ...
Plasma Flame<br />Compressed Air gas is used<br />Plasma flame: 15 cm long<br />Wave Guide 3 cm thick<br />
Cleaning Trials – Metallized Alumina<br />BEFORE<br />AFTER<br />
Ultra-Cleaning Results on Copper<br />Po210<br />Before AP<br />After AP<br />
Improvements – Vapor Added<br />Vapor Generator characterized by:<br />Operative pressure from 4 to 6 bar / from 58 to 87 ...
Improvements – Vapor Added<br />A narrowing it’s been created in the glass injector<br />Analumina capillary it’s been pla...
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Terenziani - Atmospheric microwave plasma torches for advanced cleaning

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Atmospheric Microwave plasma torches for advanced cleaning (Giovanni Terenziani - 30')
Speaker: Giovanni Terenziani - Legnaro National Laboratories - INFN | Duration: 30 min.
Abstract
During the last years of research in the plasma field, more and more importance has been focused on Atmospheric Plasma sources. One of the biggest and most important possible application is to use them like a ultra-cleaning device. In fact experiments on Uranium or Thorium contaminated samples have shown that an Atmospheric Plasma surface treatments can decrease significantly the amount of contaminant species without adding any unwanted contamination. These experiments have been taken during the creation of an ultra-cleaning protocol for the C.U.O.R.E. experiment.
This kind of results can also open great possibilities in the field of superconductivity physics. In fact devices like Atmospheric Plasma torches could be used in the future to clean the inside surface of resonant cavities used in the particle accelerators.
During my work at Legnaro National Laboratories in the National Institute of Nuclear Physics I’ve developed an Atmospheric Plasma Semi-Metallic Torch. The principal aim of this device was to lower the content of radioactive contaminant in some Copper samples. The experimental results were encouraging and the study in this field seems to be very fruitful.
One of the possible improvement that we took into account was the possibility of increase the ionized species population by adding to the carrier gas different miscellaneous of various gases or liquid. In particular it’s been noticed, from the literature, the strong effect produced by the O+ and O++ particles. Because of this, we thought that adding water vapor in the gas carrier flux can provide good improvement in the O+ and O++ population. So we reach what we called “The Burning Water Configuration”. The main idea was to introduce a water vapor flux, produced by a vapor generator, directly into the plasma in order to “burn” the biggest quantity of the water possible. Problems with pressure and temperature of the vapor was solved. In fact the condensation of the water on the quartz tube walls, even in the plasma region, could decrease the quantity of “burned” vapor. Increasing then the working temperature and decreasing the flux we reached a minimum in the condensation regime and the plasma with vapor has been obtained.
A new development of this plasma source, for treating cavities, can be the creation of a bended plasma. This can be obtained by using a particular angular tube placed by the end of the plasma torch. This, with the help of a turbulent flux regime, can guide the plasma through the bended tube without hitting walls, avoiding in this case the melting of the tubes. With the possibility to bend the plasma flame we can be able to reach the most difficult part of the inner cavities surface. This should ensure more flexibility of operation to the whole system referring also to any other application field.

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Terenziani - Atmospheric microwave plasma torches for advanced cleaning

  1. 1. Atmospheric Microwave Plasma Torches for Advanced Cleaning<br />Giovanni Terenziani<br />FabrizioStivanello<br />Antonio Alessandro Rossi<br />
  2. 2. Outline<br />Plasma Introduction<br /><ul><li>LTE or Non-LTE and Classification</li></ul>Our Configuration<br /><ul><li>Semi-Metallic Torch
  3. 3. Cleaning Experiments
  4. 4. Results</li></ul>Improvements<br /><ul><li>Vapor
  5. 5. Cut Off
  6. 6. Plasma Bending</li></ul>Final Considerations<br />
  7. 7. Plasma’s Pressure Regimes<br />PlasmasNon in Local Thermodynamic<br />Equilibrium (Non-LTE plasma)<br />Plasmas in Local Thermodynamic Equilibrium (LTE plasma)<br /><ul><li>Te= Th
  8. 8. Electron density: 1021 – 1026 m-3
  9. 9. Inelastic collision create reactive species
  10. 10. (elastic one heat heavy particle)
  11. 11. Te >> Th
  12. 12. Electron density: <1019 m-3
  13. 13. Inelastic collision induce the plasma chemistry
  14. 14. (elastic slightly raise heavy particle kinetic energy)</li></li></ul><li>Types of Atmospheric Plasmas<br />DC and low frequency discharge<br />RF waves<br />Microwaves discharge<br />Industrial sources<br />Arc torch<br />Corona and DBD <br />(pulsed DC)<br />ICP (Inductivelycoupled plasma)<br />IST (pulsed)<br />Laboratorydevelopment<br />Microplasma<br />APPJ, cold plasma torch, hollow cathode, microplasma CCμP<br />TIA (torche à injection axiale), <br />MTD (Microwave torch discharge),<br /> MPJ (Microwave plasma jet),<br /> MPT (Microwave plasma torch)<br />
  15. 15. Types of Atmospheric Plasmas<br />DC and low frequency discharge<br />RF waves<br />Microwaves discharge<br />Industrial sources<br />Arc torch<br />Corona and DBD <br />(pulsed DC)<br />ICP (Inductivelycoupled plasma)<br />IST (pulsed)<br />Laboratorydevelopment<br />Microplasma<br />APPJ, cold plasma torch, hollow cathode, microplasma CCμP<br />TIA (torche à injection axiale), <br />MTD (Microwave torch discharge),<br /> MPJ (Microwave plasma jet),<br /> MPT (Microwave plasma torch)<br />
  16. 16. Types of Atmospheric Plasmas<br />DC and low frequency discharge<br />RF waves<br />Microwaves discharge<br />Industrial sources<br />Arc torch<br />Corona and DBD <br />(pulsed DC)<br />ICP (Inductivelycoupled plasma)<br />IST (pulsed)<br />Laboratorydevelopment<br />Microplasma<br />APPJ, cold plasma torch, hollow cathode, microplasma CCμP<br />TIA (torche à injection axiale), <br />MTD (Microwave torch discharge),<br /> MPJ (Microwave plasma jet),<br /> MPT (Microwave plasma torch)<br />
  17. 17. Semi Metallic Plasma Torch<br />
  18. 18. General Structure of a Plasma Torch<br /><ul><li>A microwave source (Amplifier, generator)
  19. 19. Microwave equipment (wave guide, tuning system, circulator)
  20. 20. An ignition system
  21. 21. A gas nozzle (a quartz tube with flowing gas)</li></li></ul><li>3-T Plasma rules<br />Plasma is ruled by 3 T-factors:<br />Time<br />Turbulence<br />Temperature<br />Properties<br />of Plasma<br />Duration of the plasma<br />Can confine Plasma<br />to avoid unwanted burnings<br />Can improve the stability of the Plasma flame<br />
  22. 22. Plasma Flame<br />Compressed Air gas is used<br />Plasma flame: 15 cm long<br />Wave Guide 3 cm thick<br />
  23. 23. Cleaning Trials – Metallized Alumina<br />BEFORE<br />AFTER<br />
  24. 24. Ultra-Cleaning Results on Copper<br />Po210<br />Before AP<br />After AP<br />
  25. 25. Improvements – Vapor Added<br />Vapor Generator characterized by:<br />Operative pressure from 4 to 6 bar / from 58 to 87 psi <br />Vapor temperature from 155 to 160° C <br />Vapor capacity 62 g/min. max.   <br />
  26. 26. Improvements – Vapor Added<br />A narrowing it’s been created in the glass injector<br />Analumina capillary it’s been placed at the end of the vapor injector<br />Vapor Inlet<br />a<br />b<br />Air Inlet<br />Alumina Capillary<br />
  27. 27.
  28. 28. Improvements – Vapor Added<br />
  29. 29. Considerations – Vapor Added<br />Flushing Vapor inside<br />Plasma unstable<br />Possible explanations:<br /><ul><li>Water drop capture negative charges, so plasma slowly turns off
  30. 30. Some water lying in the bottom part of the tube can absorb microwave</li></li></ul><li>Improvements – Cut Off<br />Help to bring out more microwave from guide<br />Elongation of the Plasma Flame<br />Cut Off<br />Air <br />Inlet<br />
  31. 31. Plasma Flames with and without Cut-Off<br />17 cm<br />10 cm<br />
  32. 32. Improvements – Plasma Bending<br />Pyrex Glass<br />
  33. 33.
  34. 34. Possible Applications – Cavities Treatment?<br />1.5 GHz Cavity<br />Bended Quartz Tube<br />
  35. 35. Final Considerations<br /><ul><li>Ultra-cleaning with atmospheric plasma is possible
  36. 36. Enhancement of O+ and O++is possible by adding water vapor
  37. 37. Application in the RF Superconductivity Physics for surface treatment of cavities
  38. 38. Future development: Microwave Gun</li></li></ul><li>Thanks for your attention!<br />
  39. 39. Microwave Source – The Magnetron<br />Supplyconnectors<br />Cooling Fins<br />Antenna<br />
  40. 40. Microwave Source – The Magnetron<br />Antenna<br />Anodic Cavities<br />Cathode emitting e-<br />
  41. 41. Microwave Equipment<br />Circulator: protects Magnetron <br />from back-scattered wave<br />3-Stub Tuner: used to determine the<br />right position of E field maximum<br />
  42. 42. Microwave Equipment<br />Wave Guide<br />Hole for the quartz tube<br />( Position of max E field)<br />
  43. 43. Analysis of I-V Curve with double LP<br />To evaluate the electron temperature we track a parallel to x axisand the intercept with the interpolation of the curve in the concavity changing point gives the value of 2kTe/e<br />So kTe/e ≈ 9.65 eV<br />Te = 11400 K ??????? <br />
  44. 44. Primary electrons measure?<br />Double Probe<br />Double Probe ruled by primary e-<br />
  45. 45. Our Results<br />

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