Technical Challenges and R&D Progress at Bates for MIT X-ray Laser Facilities
This presentation outlines the critical technical challenges in developing a cutting-edge Free Electron Laser (FEL) facility at Bates Laboratory, including achieving synchronization between FEL output and various laser systems, ensuring RF stability, and enhancing energy stability for user operations. Highlights include the R&D program advancements such as the development of a high-repetition-rate photoinjector, tunable seed lasers, and the integration of new diagnostic technologies. The goal is to enable precise experiments and innovations in coherent optical beam handling, facilitating groundbreaking research opportunities.
Technical Challenges and R&D Progress at Bates for MIT X-ray Laser Facilities
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Presentation Transcript
R&D at Bates William S. Graves MIT-Bates Laboratory Presentation to MIT X-ray laser Accelerator Science Advisory Committee September 18-19, 2003
Technical Challenges • Achieve ~10 fs timing synchronization between FEL output, seed lasers, and pump-probe lasers. • Necessary RF phase and amplitude stability for timing above. • Stability in energy per pulse, timing, and pointing appropriate for a user facility. • Reduced power consumption for CW operation. • Reliable laser seed generation including tunability and stability. • Development of fast RF or ferrite switches necessary to deliver beam to multiple undulators. • Development of a high repetition rate, high brightness photoinjector. • Development of tunable undulators. Matching of undulator resonance. Orbit correction over tuning range. • Electron beam diagnostics. • Coherent photon beam diagnostics at short wavelength.
Bates accelerator layout 200 m Energy compressor chicane R56 = -3400 mm 500 MeV per pass 1 kHz rep rate 2856 MHz DC photoinjector GaAs cathode 360 kV thermionic source
R&D program at Bates • Demonstrate some of the key technologies at lower energy including • Development of stable HHG seed source. • Seeding FEL with ultrashort HHG pulses. • Development of tunable seed laser • Cascaded HGHG FEL output • Cascaded HGHG at BNL • Timing synchronization of FEL, seed, and pump lasers below 100 fs • Timing synchronization of laser and RF and e-beam. • Support for LUX injector development. An FEL using an upgraded Bates linac could drive a 10 nm FEL enabling prototype user experiments and development of coherent optical beam handling methods.
Hardware for R&D program • Equipment to be added includes • S-band photoinjector • Chicane bunch compressor? • Multiple undulators • Ti:Sapp and equipment for HHG seed generation • Diagnostics • RF upgrade or cryomodules? • Photon beamlines
Bates Modulators A. Zolfaghari, W. North New Solid State Modulator deck with Switch Tubes • Switch-Tube Specifications • Maximum Operating Hold-Off Voltage 175kV • Maximum Peak Pulse Current 50 Amps per output • (100A total) • Minimum voltage across the modulator 18kV • Output Pulse Duration 0-55s • Maximum Duty factor 4% • (limited by Switch Tube Cooling) • Maximum Pulse Repetition 5kHz • Short Term Stability 0.02% • Current to 80A (fixed beam • switch tube collector voltage) Rise: 0.6s Fall: 0.2s Solid-State Switch Specifications High voltage Input 1-17.5kV DC (positive polarity) Maximum Pulse Current 75 A 1 sec Peak Current 100 A Intrapulse Voltage Drop <200V @ 100 A Pulse Width 1 to 50 sec Maximum Repetition Rate 5 kHz Rise Time ~ 1 sec Fall Time load dependent Cooling Passive Oil Cooling Maximum Power Dissipation 3,000 W
Schedule • Laser/RF timing synchronization currently under development (Kaertner group). • NSF and DOE expected to solicit accelerator R&D proposals for FY05. • Submit proposal by 1/04
Budget • Laser timing measurements ~$20k + postdoc • HGHG cascade at BNL ~$100k? • S-band injector at Bates ~$1M • Undulator at Bates ~$1-2M • RF upgrade at Bates ~$4M for 1 GeV single pass • Test RF recycler at BESSY ~$20k • Modulator for LUX ~$300k • Fast e-beam switch ~$100k • HHG seed generation $1M
