Overview of the latest SRF
projects at the S-DALINAC*




                           Sven Sievers

                       ...
Outline

• Overview of the S-DALINAC

• SRF at the S-DALINAC

• Vertical bath cryostat

• Latest measurements
  • Piezo-Ac...
Overview of the S-DALINAC




Design values:                                 Max. energy:                130 MeV
         ...
Overview of the S-DALINAC




04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
Overview of the S-DALINAC




04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
SRF at the S-DALINAC




   Material:                         Niob (RRR=300)                        Length:      1m
   Fre...
Vertical bath cryostat

Diameter:                                                      35 cm
Depth:                       ...
Vertical bath cryostat




04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
Vertical bath cryostat

Operation characteristics
• Cooldown 300 K → 4 K                                                  ...
First measurements: Piezo Actor

                         Investigation of the stroke of a piezo-actor @ 2 K to
          ...
First measurements: Piezo Actor

      Existing tuning system: Fine tuning of cavity with magnetostrictive elements




04...
First measurements: Piezo Actor



Required frequency shift:
 1000 Hz

Resulting cavity deformation:
 2 µm

Required strok...
First measurements: Piezo Actor

Required stroke of fine tuner:                                                           ...
First measurements: Piezo Actor




04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
First measurements: OSTs

                                  Performance check of the prototypes of an
                    ...
First measurements: OSTs

OSTs shall be used for the
detection of quench positions
of superconducting cavities



The quen...
First measurements: OSTs

                                                                    R – Moment of the heat pulse...
Test in preparation: RF power couplers

                Characterisation of new power couplers for the injector upgrade


...
Test in preparation: RF power couplers

Planed injector upgrade

•    Energy increase in the injector
     section from 10...
Test in preparation: RF power couplers


        Actual power coupler:                         500 W                Qex = ...
RF power couplers


        Actual power coupler:                           500 W                 Qex = 3·106 - 1·1010

  ...
Outlook

•    Construction of Quench-Detection-Array

•    Development of optical inspection setup

•    Further investiga...
Thank you for your attention



Institut für Kernphysik, TU Darmstadt

     S. Sievers, U. Bonnes, J. Conrad, R. Eichhorn,...
04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
Closed loop for liquid Helium




04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
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Sievers - Overview of the latest SRF projects at the S-DALINAC

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Overview of the latest SRF projects at the S-DALINAC (Sven Sievers - 30')
Speaker: Sven Sievers - S-DALINAC, TU Darmstadt | Duration: 30 min.
Abstract
S. Sievers, U. Bonnes, J. Conrad, R. Eichhorn, F. Hug, M. Konrad, T. Kürzeder, N. Pietralla, A. Richter

The Superconducting Darmstadt Linear Accelerator S-DALINAC uses 3 GHz niobium cavities for electron acceleration. These cavities suffer from Q-values being three times lower than designed. Part of an explanation for these low Q-values could be surface contaminations, another possibility is the use of magnetostrictive components in the fine tuning system located directly at the cavity. Current research includes the setup of an array for quench detection via 2nd sound to find the contaminated areas, the investigation of the behaviour of piezo actors in superfluid helium to replace the magnetostrictive elements and the operation test of new power couplers.
These experiments are conducted at the vertical bath cryostat that has been commissioned within the last year. The talk will cover the latest results in these projects.

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Sievers - Overview of the latest SRF projects at the S-DALINAC

  1. 1. Overview of the latest SRF projects at the S-DALINAC* Sven Sievers TU Darmstadt Institut für Kernphysik SFB 634 *Supported by the DFG through SFB 634
  2. 2. Outline • Overview of the S-DALINAC • SRF at the S-DALINAC • Vertical bath cryostat • Latest measurements • Piezo-Actor • Oscillating Superleak Transducers • Test in preparation • RF power couplers • Outlook 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  3. 3. Overview of the S-DALINAC Design values: Max. energy: 130 MeV Energy spread: ±10-4 Max. beam current: 60 µA Duty cycle: cw 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  4. 4. Overview of the S-DALINAC 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  5. 5. Overview of the S-DALINAC 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  6. 6. SRF at the S-DALINAC Material: Niob (RRR=300) Length: 1m Frequency: 2.9975 GHz Eacc: 5 MV/m Mode: TM010,π Q0: 3·109 Temperature: 2K Pdis: 4.2 W 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  7. 7. Vertical bath cryostat Diameter: 35 cm Depth: 260 cm Minimum required LHe-level: 150 cm Maximum LHe-level: 190 cm D=3 5 cm 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  8. 8. Vertical bath cryostat 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  9. 9. Vertical bath cryostat Operation characteristics • Cooldown 300 K → 4 K ~ 1.5 h • Fill-up to maximum LHe level ~2h • Pump down to 35 mbar / 2 K ~ 2.5 h • Stand-by losses of cryostat <1W Current limitations • No pressure regulation → 35 mbar kept via cryostat heating • Operation of vertical cryostat not possible while linac is at 2 K → Measurements limited to shut downs of the S-DALINAC 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  10. 10. First measurements: Piezo Actor Investigation of the stroke of a piezo-actor @ 2 K to replace magnetostricitive elements of fine tuning system 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  11. 11. First measurements: Piezo Actor Existing tuning system: Fine tuning of cavity with magnetostrictive elements 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  12. 12. First measurements: Piezo Actor Required frequency shift: 1000 Hz Resulting cavity deformation: 2 µm Required stroke of fine tuner: 5 µm 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  13. 13. First measurements: Piezo Actor Required stroke of fine tuner: 5 µm Stroke of piezo-actor @ 300 K: 90 µm Predicted stroke @ 4 K*: 22.5 µm Measurement with simplified tuner set-up Measured frequency shift @ 4 K in LHe: ~ 1100 Hz Resulting stroke of piezo-actor: ~ 5.5 µm Measured frequency shift @ 2 K in LHe: ~ 950 Hz Resulting stroke of piezo-actor: ~ 4,75 µm *B. Sahu, G. Chowdhury, S. Ghosh, D. Kanjilal, D. Mathuria, R. Mehta, A. Pandey, P. Patra, A. Rai and A. Roy: Use of Piezo Actuator to Frequency and Phase Lock a Superconducting Quarter Wave Resonator, Proc. of the 24th Linear Accelerator Conference 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  14. 14. First measurements: Piezo Actor 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  15. 15. First measurements: OSTs Performance check of the prototypes of an Oscillating Superleak Transducer (OST) for quench localisation @ 2 K 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  16. 16. First measurements: OSTs OSTs shall be used for the detection of quench positions of superconducting cavities The quench causes a 2nd sound wave in the superfluid LHe that can be detected by the OSTs The location of the quench is determined by triangulation 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  17. 17. First measurements: OSTs R – Moment of the heat pulse 1 – Response of the 1st OST after ~ 2 ms 2 – Response of the 2nd OST after ~ 4 ms 2 R 1 2 1 R 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  18. 18. Test in preparation: RF power couplers Characterisation of new power couplers for the injector upgrade 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  19. 19. Test in preparation: RF power couplers Planed injector upgrade • Energy increase in the injector section from 10 up to 14 MeV • Increase in current from 60 μA to 150 – 250 μA 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  20. 20. Test in preparation: RF power couplers Actual power coupler: 500 W Qex = 3·106 - 1·1010 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  21. 21. RF power couplers Actual power coupler: 500 W Qex = 3·106 - 1·1010 Waveguide coupler: 2 kW Qex = 5·106 transition beam transfer transition Design: TEMF Fabrication: FZ Julich M. Kunze, W. F. O. Müller 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  22. 22. Outlook • Construction of Quench-Detection-Array • Development of optical inspection setup • Further investigations of piezo-actors • Design of new equipment for the vertical bath cryostat (Bacholer/Master thesises): • Measurement of Q-value via decay time • Design and construction of T-Map-System 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  23. 23. Thank you for your attention Institut für Kernphysik, TU Darmstadt S. Sievers, U. Bonnes, J. Conrad, R. Eichhorn, F. Hug, M. Konrad, T. Kürzeder, N. Pietralla, A. Richter 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  24. 24. 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers
  25. 25. Closed loop for liquid Helium 04. Oktober 2010 | TU Darmstadt | Institut für Kernphysik | Sven Sievers

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