1. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Low Level RF Outline Scope Local feedback loop requirements Solutions Costs How this fits into global feedback Other signals Conclusions

2. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Scope The low level RF controls system consists of RF phase and amplitude controls at these locations: Laser Gun L0-A (a.k.a. L0-1) L0-B (a.k.a. L0-2) L0 Transverse cavity L1-S L1-X L2 – using 2 klystrons to control avg phase/ampl of L2 L3 Transverse cavity L3 - here is a bit different (lots of klystrons!)

3. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Local feedback loop requirements At each of these locations, the klystron’s phase and amplitude will be controlled Inputs are listed in Appendix A Example inputs (for the gun) are: Cell 1 RF monitor. ½” heliax. Phas/ampl 5us 120 Hz Cell 2 RF monitor ½” heliax. Phas/ampl 5us 120 Hz RF in FOR. ½” heliax. Phas/ampl 5us 120 Hz

4. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Off-the-shelf solution

5. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Off-the-shelf solution Test/measure digitizer performance: when clock increases from 105 MHz to 119 MHz, are bits lost? Talking to vendors re: arbitrary function generator (ensure noise < 0.1% ) for pulse shaping with carrier board Define interface to PAD Adapt available driver and device support for digitizer to RTEMS

6. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 In-house solution

7. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 In-house solution: alternate choice Requires development of FPGA-based board with ethernet On-board processing capability for local feedback Places the digitizers next to the low noise RF components (eliminates transmission of low noise analog signals outside the chassis)

8. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 L3 solution

9. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Costs In operation, 9 instances of VME chassis: 6000 € PowerPC: 5000 USD Fast digitizer: 5000 USD Fast DAC module in carrier board: $unknown Additional digitizer for waveforms: ~3000K Analog module for temperatures: ~2000K And 1 instance (of same) for testing/spares At L3, 1 instance of VME chassis: 6000 € PowerPC: 5000 USD Additional digitizer for waveforms: ~3000K Analog module for temperatures: ~2000K

10. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 How this fits into global feedback

11. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 How this fits into global feedback

12. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 How this fits into global feedback

13. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 How this fits into global feedback

14. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 How this fits into global feedback

15. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 How this fits into global feedback

16. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Other signals – (listed in Appendix A) Control signals This is the feedback’s calculated new phase/amplitude Need pulse shaping Pulse shaping would be entered manually Don’t know where yet Very low processing load

17. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Conclusions By using multiple VME chassis (10 over injector, sectors 24 & 30), the LCLS LLRF raw signals can be processed by the CPU in time to send out phase and amplitude corrections and have them settle within a beam pulse. When there is beam, this system will integrate with the beam-based longitudinal feedback by accepting the latter’s RF phase and amplitude corrections and passing them on.

18. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Appendix A RF Cables - Monitor and Control Signals – from LCLS ESD 1.2-137 (Akre, Hill) Legend: Monitor. Feedback. Control. From RF HUT Sub-systemSignal NameCable TypeTo LocationSignal Type Laser RF Reference 1/2" HeliaxLaser RoomPhas/Ampl CW Laser Oscillator Out1/2" HeliaxLaser RoomPhas/Ampl CW 120Hz Laser Pulse1/2" HeliaxLaser RoomPhas/Ampl picoSec RF ControlRF HutPhas/Ampl CW Gun Cell 1 RF Monitor1/2" HeliaxGun Phas/Ampl 5uS 120Hz Cell 2 RF Monitor1/2" HeliaxGun Phas/Ampl 5uS 120Hz RF In FOR 1/2" HeliaxGun Phas/Ampl 5uS 120Hz RF In REFL 1/2" HeliaxGun Phas/Ampl 5uS 120Hz RF Control1/2" Heliax20-6120Hz

19. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Appendix A continued L0-A RF In FOR 1/2" HeliaxL0-1Phas/Ampl 5uS 120Hz RF In REFL1/2" HeliaxL0-1Phas/Ampl 5uS 120Hz Load FOR1/2" HeliaxL0-1Phas/Ampl 5uS 120Hz Load REFL1/2" HeliaxL0-1Phas/Ampl 5uS 120Hz RF Control1/2" Heliax20-7 120Hz L0-BRF In FOR1/2" HeliaxL0-2Phas/Ampl 5uS 120Hz RF In REFL1/2" HeliaxL0-2Phas/Ampl 5uS 120Hz Load FOR1/2" HeliaxL0-2Phas/Ampl 5uS 120Hz Load REFL1/2" HeliaxL0-2Phas/Ampl 5uS 120Hz RF Control1/2" Heliax20-8 120Hz

20. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Appendix A continued L0- Transverse RF In FOR1/2" HeliaxL0- TransversePhas/Ampl 5uS 120Hz RF In REFL1/2" HeliaxL0- TransversePhas/Ampl 5uS 120Hz Load FOR1/2" HeliaxL0- TransversePhas/Ampl 5uS 120Hz Load REFL1/2" HeliaxL0- TransversePhas/Ampl 5uS 120Hz RF Control1/2" Heliax20-5 120Hz L1-SSLED Out FOR1/2" Heliax21-1 SLED Out REFL1/2" Heliax21-1 ACC A/B In FOR1/2" Heliax21-1Phas/Ampl 5uS 120Hz ACC A/B In REFL1/2" Heliax21-1Phas/Ampl 5uS 120Hz ACC C IN FOR1/2" Heliax21-1Phas/Ampl 5uS 120Hz ACC C IN REFL1/2" Heliax21-1Phas/Ampl 5uS 120Hz Load A/B FOR1/2" Heliax21-1Phas/Ampl 5uS 120Hz Load A/B REFL1/2" Heliax21-1Phas/Ampl 5uS 120Hz Load C FOR1/2" Heliax21-1Phas/Ampl 5uS 120Hz Load C REFL1/2" Heliax21-1Phas/Ampl 5uS 120Hz RF Control1/2" Heliax21-1 120Hz

21. Dayle Kotturi Lehman Review dayle@slac.stanford.edu May 10-12, 2005 Appendix A continued L1-X KLY Out RF FOR3/8" Heliax21-2Phas/Ampl 2uS 120Hz KLY Out RF REFL3/8" Heliax21-2Phas/Ampl 2uS 120Hz ACC In FOR3/8" Heliax21-2Phas/Ampl 2uS 120Hz ACC In REFL3/8" Heliax21-2Phas/Ampl 2uS 120Hz Load FOR3/8" Heliax21-2Phas/Ampl 2uS 120Hz Load REFL3/8" Heliax21-2Phas/Ampl 2uS 120Hz FB Control3/8" Heliax21-2 120Hz L3-Transverse RF In FOR1/2" Heliax25-5APhas/Ampl 5uS 120Hz RF In REFL1/2" Heliax25-5APhas/Ampl 5uS 120Hz Load FOR1/2" Heliax25-5APhas/Ampl 5uS 120Hz Load REFL1/2" Heliax25-5APhas/Ampl 5uS 120Hz RF Control1/2" Heliax24-8 120Hz