1. Update on TERA C-band high gradient test A.D. 31-07-2013

2. First run - Test stand setup magnetron Thermo-chiller unit + temperature sensors cavity VE2098 C band coaxial magnetron Frequency range: C band (tunable) Peak out power: 2.5MW Anode voltage: ≤50kV Anode current: ≤120A Duty cycle: ≤0.001 Pulse duration: 4 µ s

3. Test stand setup cavity PMT Faraday Cup vacuum port bidirectional coupler

4. Acqusition and control system: «C-box»

5. Magnetr on Circ. + load Flange adapter RFwindow Bidirect coupler Vacuum port Splitter WG to cavity Cavity Water cooled load from PSI Line layout Without load max. pulse length ~ 1 us. With load max. pulse length ~ 2.1 us.

6. Second run - setup

7. Test setup and history Vacuum level: ~ 1 10 -7 – 1 10 -6 mbar (heavy outgassing of the load) Peak power from magnetron: 0.6 – 2.4 MW Magnetron pulse length: 1.6 – 3.6 µs Magnetron freq tuning by mech. Deformation (no direct meas. of frequency) Repetition rate: 10 Hz (15 HZ) – Vacuum limited increase in rep rate Conditioning time: – 24 hours/day x (21 days (10 HZ) + 7 days (15 Hz) ) (# pulses ~ 30 M) – RF on time ~90% (interlocks due to vacuum and cooling issues)

8. C-box screenshot -- Forward -- Reflected -- Load -- FWD-REF-LOAD -- PMT

9. Some BD pulses – BD1 (1MW-23) Reflected and load have a signal Forward pulse continues PMT sees something

10. BD2 - (1MW-24) Forward pulse stops Reflected and load drop abruptly PMT signal noisy

11. BD3 - (1MW-27) Forward pulse stops Reflected and load drop abruptly PMT signal noisy

12. BD4 – (1.1 MW-15) Reflected increases Forward pulse stops Lload drops abruptly PMT signal noisy

13. Stored energy

14. Stored energy - BD

15. Stored energy – short BD

16. BDR – T_pulse scaling

17. BDR- Esurf scaling

18. Fowler Nordheim plot Beta_FE ~ 90

19. ...to be done Validation of splitter calibration Analysis of BD-time distribution Inspection of the cavity surface