LCLS Undulator Controls

1. LCLS Undulator Controls ANL LCLS All-Hands Meeting February 20, 2006 Josh Stein Argonne National Laboratory Advanced Photon Source ASD-Controls

2. Undulator Controls overview • Major control points for the LCLS Undulator • Motion • Joe Xu, Shifu Xu • Diagnostics • Josh Stein, Eric Norum (consultant), Till Strauman (SLAC) • Beam loss monitors • Josh Stein, TBD • Magnet Power Supplies • SLAC personnel, Tom Fohrs (consultant) • General data acquisition • Josh Stein

3. Motion stages • Undulator Alignment • Cam based system • Five cam stages per undulator segment • Challenging motion algorithms due to independent stages • No hard stops or definitive “home” position • Difficult to protect vacuum chamber against unanticipated motion extremes • “Hoop and wire” system under consideration

4. Motion Stages • Undulator slide • Allows removing of the undulator from the beam line • Traditional linear type sliding stages (dual single axis) • Interesting alignment problem using linear encoders for motion feedback as well as an alignment interlock • “Comparator” based system proposed using linear potentiometers

5. Cam Motion Layout Linear Slides Undulator Segment • 5 motors for alignment • 2 motors for linear translation • 7 motors / undulator * 33 undulators = 231 motors! Eccentric Camshafts Picture courtesy Joe Xu

6. Motion Control Status • Undulator motion design very mature • Field Based IOCs – one per undulator segment • In-tunnel placement minimizes large cable runs • Stand-alone operation and network booting via DHCP • “Smart Motors” used message based control via serial port • Encoder input via on-board ADC • Software design ~80% complete • Algorithm development complete • EPICS Implementation in progress • Operator interface screens and scripts still need definition

7. Diagnostics • RFBPM • High precision (>12 bits effective) ADC required • BPM electronics dictate a sampling rate requirement of >60Mhz • Trigger rate maximum 120Hz • Must be able to trigger off of SLAC based timing system • New event system being created by LCLS/SLAC controls group based on SLS/Diamond timing system

8. BPM Controls Status • High speed ADC procured • EPICS support “expected” • Software tweaking may be necessary • Existing GTR support to be used for in-house testing and validation • ITS Support required soon • Expect to bring in outside help for effort

9. Diagnostics • Beam Finder Wire (BFW) • Pneumatically operated sensor • “Standard” scanning wire system as used at SLAC • Beam strike on wire induces signal – monitored via control system (ADC) • Timing / event system integration required • Ancillary monitoring is possible via down-stream beam loss monitors (beam scattering)

10. BFW Controls Status • “Standard” SLAC based scanning wire acquisition system to be used • “New” EPICS based scanning wire system under development by LCLS/SLAC • Investigation / design for the pneumatically operated sensor motion needs to be addressed

11. Beam Loss Monitor • Ionization type beam loss monitors • Detectors placed as rough diagnostic to determine beam loss direction • High voltage bias • New application – new “product” – investigation ongoing • Possibly integrate a Fiber Optic radiation sensing system similar to that at TESLA

12. BLM Controls Status • Expect work to begin later this year • Ionization chamber based system may require more controls design effort than originally anticipated • We expect to have a much better idea on what this system consists of within the next month • Similar research will be done with regards to the fiber-optic system • Integration into the beam stop system of the injector is also required – needs definition

13. Miscellaneous data acquisition • At present we expect to monitor about 10 temperature points for each undulator segment (including breaks) • Thermocouples and possibly (one or two) RTDs • A high data rate is not necessary, so dense multiplexing will be used to keep costs down

14. SLAC Controls effort • The LCLS Controls group at SLAC has had some interesting challenges as well: • Integrate existing SLAC based control system into a modern EPICS based IOC • Covert the SLC timing system into something more “modern” • Address the “novel” use of PLCs in safety systems

15. Undulator Hall Issues • Equipment buildings on either end of (170m) Undulator Hall • Long cable runs (some exceeding 250 feet) dictate careful planning • Two buildings to house our equipment racks on either end of Undulator hall. • Adequate planning for a possible second undulator line • Currently in the design phase with the LCLS Conventional Facilities group to assure we have adequate capacity: • Cable Trays • Power • Penetrations

16. Beam Transport Hall – 227m long above grade facility to transport the electron beam through the existing RSY • Central Lab Office Complex – office facility to house ~ 275 LCLS researchers, engineers, technicians, administrative staff and visiting experimentalists • Undulator Hall – 170m long underground tunnel housing undulators and ancillary equipment • Far Experimental Hall – underground single 46’ cavern to house 3 experimental hutches and prep space • Electron Beam Dump – 40m long underground facility used to separate the electron and x-ray beams • Front End Enclosure – 40m long underground facility to house various diagnostic equipment in support of the photon beam • Near Experimental Hall – underground facility whose primary function is to house 3 experimental hutches, prep and shops • X-Ray Transport & Diagnostics Tunnel – 210m long underground tunnel used to transport photon beams from NEH to FEH Layout courtesy David Saenz

17. Relative size of the LCLS Undulator BTH Near Hall Undulator Far Hall

18. Let’s add in the SLAC Linac

19. Controls : Installation Planning • Along with careful planning of cabling and rack layout, an installation plan is required to assure no surprises during the final stages of construction and delivery at SLAC • Most of the hardware although specified and designed at APS, will be installed by SLAC personnel – documentation needs to be thorough and complete • We expect to rely heavily on the IRMIS tool suite as a design aid in this regard

20. Near Term Goal : SUT • Support the installation of the Single Undulator Test system • Motion system • Cam calibration system • Alignment System support (esp. for position feedback) • Equipment rack mock-up (in tunnel) • Cable routing mock-up and testing • Conduct vigorous motion tests to assure adequate performance which meets or exceeds the PDR

21. Undulator Controls : Conclusion • We have concentrated our efforts on the most challenging aspect of our scope : the motion system. With that well in hand, we will begin concentrating on: • BPM and BFW acquisition • Beam Loss integration • Thermal monitoring • Installation planning • Interesting challenges are on the horizon!