FEL R&D Topics
P. Emma, J. Frisch, Z, Huang
Dec. 3, 2010 (Version 1.2)
Project Scales: [small] <1 M$,
[medium]: 1-10 M$,
[large] >10 M$
(no priorities yet)
1. FEL Self-Seeding Development
a) Test the Geloni hard x-ray scheme on LCLS-I (DESY 10-133) and extended selfseeding to longer bunches and harder x-rays [small]
b) Upgrade LCLS-II SXR undulator with chicane, monochromator, and extended
undulator [large]
2. Injector Test Facility (ITF) – Beam Brightness Generation and Preservation
a) Short-term development of the LCLS-II injector at sector-10 with load-lock for
cathode research [small, since LCLS-II will be built anyway]
b) Long-term ITF development at sector-0 with 2nd phase including connection to
linac, bunch compression test area, and possibly emittance exchange [large]
c) R&D on high-charge/low-emittance beams in support of THz generation or long
wavelength FELs. [small, if TF exists]
3. Harmonic Generation and External Seeding
a) Echo R&D toward higher harmonics [medium - ongoing]
b) Develop low phase noise lasers to allow Echo at high harmonics [medium]
c) Finish second harmonic after burner studies (SHAB) [small - ongoing]
d) R&D on propagation of -bunched electron beams [small]
e) Build Echo or HGHG test system using ITF + linac at a few GeV [large]
4. Temporal Diagnostics for Extremely Short Electron and/or X-Ray Pulses
a) A-line method using high resolution electron spectrometer [small - ongoing]
b) X-band transverse RF deflector [medium - started]
c) Multi-channel COTR spectrometer [small - started]
d) THz-to-optical electron and x-ray streak methods [small scale]
e) Develop x-ray arrival time measurements [medium]
f) Develop statistical methods to measure x-ray pulse length [small - ongoing]
5. Bunch Compression Research
a) Continued study on CSR at LCLS-I, including over-compression methods, phase
advance CSR cancellation, modeling and comparison to data, etc. [small]
b) Linearization using magnetic methods rather than harmonic RF (part of ITF)
[small, if ITF compressor test area available]
c) Further studies on -bunching instability (modulate LCLS beam and measure
gain) [small]
d) R&D on improved RF phase and amplitude jitter [medium?]
6. X-Ray Polarization Control
a) Add APPLE undulator after LCLS-I undulator, but with appropriate K for
efficiency and adequate power, etc. [medium– ongoing?]
b) Add phase shifter to APPLE system and test crossed-undulator method and
polarization switching speed [small, if APPLE device available]
c) Develop polarization measurement techniques [medium?]
d) Test polarization control of hard x-rays using crystals [small]
7. Multi-bunch Linac/FEL Operations
a) Further testing (2 or more bunches) in LCLS to study trajectory and energy
equalization, plus independent x-ray power control on each pulse [small]
b) Computer studies to optimize bunch spacing number of bunches [small]
c) Develop and test multi-bunch diagnostics (BPMs, fast CSR-based bunch-length
monitors, gated wire-scanner detectors) [small, for prototype development]
d) Develop fast/stable kickers and optics for multi-bunch switching [medium?]
e) Multi-bunch controls and feedback development [small]
8. Manipulation of Electron Beam with Optical Lasers
a) Enhanced-SASE (ESASE) in LCLS-I (PRSTAB 8, 040701, 2004) [medium scale]
b) Use ESASE in conjunction with HXRSS scheme to seed the full ESASE pulse
train [small, if ESASE & HXRSS available]
c) Test optical FEL electron beam conditioning scheme [medium]
d) Test drive laser modulation idea to pre-bunch electron beam for FEL [small]
e) Use existing laser heater (chicane OFF) to test pre-bunching [small]
9. THz Radiation Production and Transport
a) Research most efficient ways to couple out THz (OTR, undulator, bend
magnet) [small - ongoing]
b) Develop 100-MeV electron injector, with extreme compression, to generate
very high power THz for LCLS users [medium]
c) Develop THz transport [medium?]
10. Theory and Simulation Support for Advanced FEL and Accelerator Modeling
a) Improved CSR and -bunching modeling [small]
b) FEL code development for faster start-to-end simulations [small]
c) R&D on novel FEL schemes [small]