XTCAV X-Band Transverse Deflecting Cavity Project Overview

1. XTCAVX-Band Transverse Deflecting Cavity Project Overview Patrick Krejcik Yuantao Ding, Joe Frisch

2. Layout of the Undulator to Dump Beam Line

3. Simulation example - Yuantao Dinglow charge 20pC soft x-rays FEL ON FEL OFF OTRDMP head X-ray “measurement” Current “measurement”

4. Penetration to B921 Penetration XTCAV Proposed Location

5. Conceptual sketch of the x-band structure and waveguide on the beam line.

6. Structure Fabrication • One structure built and tested • Second structure • Support stand, beam line and vacuum installation • ~$390k 1 m

7. B921 and undulator tunnel elevation view showing penetration for waveguide to the XTCAV

8. Excerpt from the floor plan of B921 with proposed modulator and klystron locations

9. B921 floor space for modulator and klystron Penetration

10. B921 cross-section showing available elevation with respect to cable trays and ceiling

11. Commercially available Modulatorinstallation housing the SLAC XL4 klystron. • Much better pulse stability than SLAC modulator: 30 ppmversus 100 ppm • Complete system houses klystron, magnet, oil tank and output transformer • EPICS controls interface • “turn-key” system purchase price ~$650k • LCLS motivated to evaluate this modulator for other applications e.g. L1S • Also purchased by LLNL, Trieste, CLS, CERN …

12. Output from the klystron goes through a mode converter to circular waveguide for lower power loss Fabrication and installation of waveguide components: including converters splitters, couplers, loads and vacuum components, all based on existing SLAC X-band designs ~$365k

13. LLRF Phase reference • Share the low-noise 476 MHz heliax from the linac with the beam phase monitor • Beam based feedback corrects slow drifts 476 MHz XTCAV Cavity

14. EPICS Controls • LLRF - (next slide) • Vacuum - status of new pumps, gauges and valves • Profile Monitor OTRDMP - present camera is only 10 Hz (upgrade?) • Feedback • orbit at BPMUE1, BPMUE2 and BPMUE3 after the XTCAV to stabilize the RF phase of cavity and keep the bunch at the zero phase crossing • PPS • Modulator interlocked to Access state • Review to show existing BTMs give adequate coverage • BCS • New spoiler at end of XTCAV • Review to show existing PICs give adequate coverage • MPS • Set threshold of MPS BLMs lower than BCS PICs

15. Why PPS, BCS and MPS are important • Beam at the wrong phase can be kicked by up to 10 mrad • Lowest energy beam, highest amplitude RF, phase at crest • Beam leaves the beam pipe within the XTCAV already • Existing safety systems have large acceptance angle. e.g. BTMs

16. LLRF EPICS Controls • Use LCLS PADs and PACs with EPICS IOC and BSA • Use either MKSU II for klystron and modulator interlocks, or Scandinova integrated controls • In the linac CAMAC PDU still provides timing to the modulator via the PIOP module • Consider the LLRF control system as a whole: • The XTCAV will be the first stand-alone RF station with EPICS-only controls • There are choices of platforms on which to implement EPICS • Linac Phase I upgrade with EPICS driver for CAMAC • Replace CAMAC modules with VME modules and EPICS timing, similar to existing EPICS architecture. • Develop a new mTCA platform • Need to be able to this in < 2 years • The choice we make here will set a precedent for the LCLS-2 injector project

17. Cost Summary