1. X-Band Test Stands: Conditioning and Operational Algorithms Joseph Tagg National Instruments Switzerland

2. Agenda System goal Software architecture Algorithm description – Tuning – Conditioning 26-Jan-15CLIC Workshop 2015 - Joseph Tagg

3. System goal Each accelerating structure needs a few thousand hours of high power RF conditioning The purpose of the software is to automate the X-band test stands to run 24/7. -Automatically increase power over time -Tune pulse compressor (XBOX1) 26-Jan-15CLIC Workshop 2015 - Joseph Tagg

4. Software Versions XBOX1 software – TERA CBOX – CTF Dogleg XBOX2 software – SLAC XBOX – XBOX3 Further external interest – CPI – TERA TULIP 26-Jan-15CLIC Workshop 2015 - Joseph Tagg

5. Software Architecture Waveform Acquisition RF Gen. RF Output Control AnalysisMonitoringPC Tuning PC Stepper Motors 26-Jan-15CLIC Workshop 2015 - Joseph Tagg Log Single-point Acquisition

6. Software Architecture Waveform Acquisition RF Gen. RF Output Control AnalysisMonitoringPC Tuning PC Stepper Motors 26-Jan-15CLIC Workshop 2015 - Joseph Tagg Log Single-point Acquisition

7. Pulse Compressor Tuning (XBOX1) PC Cavity Encoder read-out Stepper control Temperature changes lead to: Loss of performance  Total volume offset Increased reflection back to the klystron  Relative volume offset 26-Jan-15CLIC Workshop 2015 - Joseph Tagg Photo by Ben Woolley

8. Tuning Indicators 26-Jan-15CLIC Workshop 2015 - Joseph Tagg Position of dip Slope of flat top

9. PC Tuning Algorithm Loop (XBOX1) if reflected_dip > limit: change one cavity volume if things get worse: inverse direction of change else: if slope good: work on power amplitude PID else: change volume of both cavities if things get worse: inverse direction of change 26-Jan-15CLIC Workshop 2015 - Joseph Tagg

10. Pulse Compressor Tuning (XBOX2) Water-cooled PC cavities Programmable chiller units maintain temperature No further automatic control at this time 26-Jan-15CLIC Workshop 2015 - Joseph Tagg Photo by Ben Woolley

11. Software Architecture Waveform Acquisition RF Gen. RF Output Control AnalysisMonitoringPC Tuning PC Stepper Motors 26-Jan-15CLIC Workshop 2015 - Joseph Tagg Log Single-point Acquisition

12. Power/Conditioning Control Fast – second – PID loop on the incident power to the structure Medium – minutes – increase power by 10kW every few minutes if no BD – reduce power by 10kW if successive BDs too close in time Slow – hours – BDR measurement and stop power increase if it is too high – Moving average of 1M pulses 26-Jan-15CLIC Workshop 2015 - Joseph Tagg

13. Conditioning on Vacuum When outgassing is the limiting factor Replace medium-term algorithm to stabilize at a specified pressure Allows conditioning of any high-power RF device 26-Jan-15CLIC Workshop 2015 - Joseph Tagg

14. CTF Dogleg Amplitude Control Requires 2 setpoints: – With beam present – Without beam present Increase power when beam detected React to beam loss by immediately reducing power output to pre-beam levels 26-Jan-15CLIC Workshop 2015 - Joseph Tagg

15. Dogleg Beam Loading 26-Jan-15CLIC Workshop 2015 - Joseph Tagg RF Ready RF Nominal Ramp up RF + beam RF not Ready Ramp up RF No RF S E Image by Luis Navarro

16. Phase Control (XBOX2) Phase is controlled to flatten the top of the pulse A_setamplitude setpoint Acurrent amplitude ratescaling for speed ɸ out_new = ɸ out + (A_set – A) * rate 26-Jan-15CLIC Workshop 2015 - Joseph Tagg

17. XBOX1 Results 26-Jan-15CLIC Workshop 2015 - Joseph Tagg 100 MV/m

18. Thank you for your attention. Questions? 26-Jan-15CLIC Workshop 2015 - Joseph Tagg