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Title: R&D for a Soft X-Ray Free Electron Laser Facility

Abstract

Several recent reports have identified the scientific requirements for a future soft x-ray light source, and a high-repetition-rate free-electron laser (FEL) facility that is responsive to these requirements is now on the horizon. R&D in some critical areas is needed, however, to demonstrate technical performance, thus reducing technical risks and construction costs. Such a facility most likely will be based on a CW superconducting linear accelerator with beam supplied by a high-brightness, high-repetition-rate photocathode electron gun operating in CW mode, and on an array of FELs to which the accelerated beam is distributed, each operating at high repetition rate and with even pulse spacing. Dependent on experimental requirements, the individual FELs can be configured for either self-amplified spontaneous emission (SASE), seeded, or oscillator mode of operation, including the use of high-gain harmonic generation (HGHG), echo-enhanced harmonic generation (EEHG), harmonic cascade, or other configurations. In this White Paper we identify the overall accelerator R&D needs, and highlight the most important pre-construction R&D tasks required to value-engineer the design configuration and deliverables for such a facility. In Section 1.4 we identify the comprehensive R&D ultimately needed. We identify below the highest-priority requirements for understanding machine performance and reduce risk and costs atmore » this pre-conceptual design stage. Details of implementing the required tasks will be the subject of future evaluation. Our highest-priority R&D program is the injector, which must be capable of delivering a beam with bunches up to a nanocoulomb at MHz repetition rate and with normalized emittance {le} 1 mm {center_dot} mrad. This will require integrated accelerating structure, cathode, and laser systems development. Cathode materials will impact the choice of laser technology in wavelength and energy per pulse, as well as vacuum requirements in the accelerating structure. Demonstration experiments in advanced seeding techniques, such as EEHG, and other optical manipulations to enhance the FEL process are required to reduce technical risk in producing temporally coherent and ultrashort x-ray output using optical seed lasers. Success of EEHG in particular would result in reduced development and cost of laser systems and accelerator hardware for seeded FELs. With a 1.5-2.5 GeV linac, FELs could operate in the VUV-soft x-ray range, where the actual beam energy will be determined by undulator technology; for example, to use the lower energy would require the use of advanced designs for which undulator R&D is needed. Significant reductions in both unit costs and accelerator costs resulting from the lower electron beam energy required to achieve lasing at a particular wavelength could be obtained with undulator development. Characterization of the wakefields of the vacuum chambers in narrow-gap undulators will be needed to minimize risk in ability to deliver close to transform limited pulses. CW superconducting RF technology for an FEL facility with short bunches at MHz rate and up to mA average current will require selection of design choices in cavity frequency and geometry, higher order mode suppression and power dissipation, RF power supply and distribution, accelerating gradient, and cryogenics systems. R&D is needed to define a cost and performance optimum. Developments in laser technology are proceeding at rapid pace, and progress in high-power lasers, harmonic generation, and tunable sources will need to be tracked.« less

Authors:
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Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE; Accelerator& Fusion Research Division; Advanced Light Source Division; Engineering Division
OSTI Identifier:
964409
Report Number(s):
LBNL-2169E
TRN: US0903950
DOE Contract Number:  
AC02-05CH11231
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATORS; CATHODES; CONFIGURATION; CRYOGENICS; ELECTRON BEAMS; ELECTRON GUNS; FREE ELECTRON LASERS; GEOMETRY; HARMONIC GENERATION; HARMONICS; LASERS; LIGHT SOURCES; LINEAR ACCELERATORS; OSCILLATORS; PHOTOCATHODES; WAVELENGTHS; WIGGLER MAGNETS; SOFT X RADIATION; light sources, x-ray, free electron laser

Citation Formats

Corlett, John, Attwood, David, Byrd, John, Denes, Peter, Falcone, Roger, Heimann, Phil, Leemans, Wim, Padmore, Howard, Prestemon, Soren, Sannibale, Fernando, Schlueter, Ross, Schroeder, Carl, Staples, John, Venturini, Marco, Warwick, Tony, Wells, Russell, Wilcox, Russell, Zholent, Alexander, Adolphsen, Chris, Arthur, John, Bergmann, Uwe, Cai, Yunhai, Colby, Eric, Dowell, David, Emma, Paul, Fox, John, Frisch, Josef, Galayda, John, Hettel, Robert, Huang, Zhirong, Phinney, Nan, Rabedeau, Tom, Raubenheimer, Tor, Reis, David, Schmerge, John, Stohr, Joachim, Stupakov, Gennady, White, Bill, and Xiang, Dao. R&D for a Soft X-Ray Free Electron Laser Facility. United States: N. p., 2009. Web. doi:10.2172/964409.
Corlett, John, Attwood, David, Byrd, John, Denes, Peter, Falcone, Roger, Heimann, Phil, Leemans, Wim, Padmore, Howard, Prestemon, Soren, Sannibale, Fernando, Schlueter, Ross, Schroeder, Carl, Staples, John, Venturini, Marco, Warwick, Tony, Wells, Russell, Wilcox, Russell, Zholent, Alexander, Adolphsen, Chris, Arthur, John, Bergmann, Uwe, Cai, Yunhai, Colby, Eric, Dowell, David, Emma, Paul, Fox, John, Frisch, Josef, Galayda, John, Hettel, Robert, Huang, Zhirong, Phinney, Nan, Rabedeau, Tom, Raubenheimer, Tor, Reis, David, Schmerge, John, Stohr, Joachim, Stupakov, Gennady, White, Bill, & Xiang, Dao. R&D for a Soft X-Ray Free Electron Laser Facility. United States. https://doi.org/10.2172/964409
Corlett, John, Attwood, David, Byrd, John, Denes, Peter, Falcone, Roger, Heimann, Phil, Leemans, Wim, Padmore, Howard, Prestemon, Soren, Sannibale, Fernando, Schlueter, Ross, Schroeder, Carl, Staples, John, Venturini, Marco, Warwick, Tony, Wells, Russell, Wilcox, Russell, Zholent, Alexander, Adolphsen, Chris, Arthur, John, Bergmann, Uwe, Cai, Yunhai, Colby, Eric, Dowell, David, Emma, Paul, Fox, John, Frisch, Josef, Galayda, John, Hettel, Robert, Huang, Zhirong, Phinney, Nan, Rabedeau, Tom, Raubenheimer, Tor, Reis, David, Schmerge, John, Stohr, Joachim, Stupakov, Gennady, White, Bill, and Xiang, Dao. Mon . "R&D for a Soft X-Ray Free Electron Laser Facility". United States. https://doi.org/10.2172/964409. https://www.osti.gov/servlets/purl/964409.
@article{osti_964409,
title = {R&D for a Soft X-Ray Free Electron Laser Facility},
author = {Corlett, John and Attwood, David and Byrd, John and Denes, Peter and Falcone, Roger and Heimann, Phil and Leemans, Wim and Padmore, Howard and Prestemon, Soren and Sannibale, Fernando and Schlueter, Ross and Schroeder, Carl and Staples, John and Venturini, Marco and Warwick, Tony and Wells, Russell and Wilcox, Russell and Zholent, Alexander and Adolphsen, Chris and Arthur, John and Bergmann, Uwe and Cai, Yunhai and Colby, Eric and Dowell, David and Emma, Paul and Fox, John and Frisch, Josef and Galayda, John and Hettel, Robert and Huang, Zhirong and Phinney, Nan and Rabedeau, Tom and Raubenheimer, Tor and Reis, David and Schmerge, John and Stohr, Joachim and Stupakov, Gennady and White, Bill and Xiang, Dao},
abstractNote = {Several recent reports have identified the scientific requirements for a future soft x-ray light source, and a high-repetition-rate free-electron laser (FEL) facility that is responsive to these requirements is now on the horizon. R&D in some critical areas is needed, however, to demonstrate technical performance, thus reducing technical risks and construction costs. Such a facility most likely will be based on a CW superconducting linear accelerator with beam supplied by a high-brightness, high-repetition-rate photocathode electron gun operating in CW mode, and on an array of FELs to which the accelerated beam is distributed, each operating at high repetition rate and with even pulse spacing. Dependent on experimental requirements, the individual FELs can be configured for either self-amplified spontaneous emission (SASE), seeded, or oscillator mode of operation, including the use of high-gain harmonic generation (HGHG), echo-enhanced harmonic generation (EEHG), harmonic cascade, or other configurations. In this White Paper we identify the overall accelerator R&D needs, and highlight the most important pre-construction R&D tasks required to value-engineer the design configuration and deliverables for such a facility. In Section 1.4 we identify the comprehensive R&D ultimately needed. We identify below the highest-priority requirements for understanding machine performance and reduce risk and costs at this pre-conceptual design stage. Details of implementing the required tasks will be the subject of future evaluation. Our highest-priority R&D program is the injector, which must be capable of delivering a beam with bunches up to a nanocoulomb at MHz repetition rate and with normalized emittance {le} 1 mm {center_dot} mrad. This will require integrated accelerating structure, cathode, and laser systems development. Cathode materials will impact the choice of laser technology in wavelength and energy per pulse, as well as vacuum requirements in the accelerating structure. Demonstration experiments in advanced seeding techniques, such as EEHG, and other optical manipulations to enhance the FEL process are required to reduce technical risk in producing temporally coherent and ultrashort x-ray output using optical seed lasers. Success of EEHG in particular would result in reduced development and cost of laser systems and accelerator hardware for seeded FELs. With a 1.5-2.5 GeV linac, FELs could operate in the VUV-soft x-ray range, where the actual beam energy will be determined by undulator technology; for example, to use the lower energy would require the use of advanced designs for which undulator R&D is needed. Significant reductions in both unit costs and accelerator costs resulting from the lower electron beam energy required to achieve lasing at a particular wavelength could be obtained with undulator development. Characterization of the wakefields of the vacuum chambers in narrow-gap undulators will be needed to minimize risk in ability to deliver close to transform limited pulses. CW superconducting RF technology for an FEL facility with short bunches at MHz rate and up to mA average current will require selection of design choices in cavity frequency and geometry, higher order mode suppression and power dissipation, RF power supply and distribution, accelerating gradient, and cryogenics systems. R&D is needed to define a cost and performance optimum. Developments in laser technology are proceeding at rapid pace, and progress in high-power lasers, harmonic generation, and tunable sources will need to be tracked.},
doi = {10.2172/964409},
url = {https://www.osti.gov/biblio/964409}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2009},
month = {6}
}