Recent reports have identified the scientific requirements for a future soft x-ray light source a... more Recent reports have identified the scientific requirements for a future soft x-ray light source and a high-repetition-rate FEL facility responsive to them is being studied at LBNL. The facility is based on a CW superconducting linear accelerator with beam supplied by a high-brightness, high-repetition-rate photocathode electron gun, and on an array of FELs to which the beam is distributed, each operating at high repetition rate and with even pulse spacing. Dependent on the experimental requirements, the individual FELs may be configured for either SASE, HGHG, EEHG, or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format ranging from sub-femtoseconds to hundreds of femtoseconds. We are developing a design concept for a 10-beamline, coherent, soft x-ray FEL array powered by a 2.5 GeV superconducting accelerator operating with a 1 MHz bunch repetition rate. Electron bunches are fanned out through a spreader, distributing be...
We report recent progress on the design of a normal conducting CW electron gun, APEX-II (Advanced... more We report recent progress on the design of a normal conducting CW electron gun, APEX-II (Advanced Photo-injector EXperiment-II) at Lawrence Berkeley National Laboratory. APEX-II is an upgrade of the successful APEX gun and the LCLS-II (Linac Coherent Light Source-II) injector, aiming at applications for Free electron laser (FEL) such as LCLS-II High Energy upgrade, UED (Ultrafast Electron Diffraction) and UEM (Ultrafast Electron Microscopy). The APEX-II adopted a two-cell cavity design with resonant frequency of 162.5 MHz. The APEX-II gun is targeting to achieve exceeding 30 MV/m of launch gradient at the cathode and output energy above 1.5 MeV with transverse emittance of 0.1 um at 100 pC. Advanced MOGA optimization technique has been used for both the RF cavity design and extensive beam dynamics studies using APEX-like and LCLS-II like injector layout. Detailed RF designs, beam dynamics studies, preliminary engineering design and FEA analysis will be presented, with cavity feature...
The Advanced Photo-injector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL)... more The Advanced Photo-injector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL) is dedicated to the demonstration of the capability of an electron injector based on the VHF-gun, the new concept RF gun developed at LBNL, of delivering the beam quality required by MHz-class repetition rate X-Ray free electron lasers. Project status, plans, and recent results are presented.
A high repetition rate, MHz, electron source is a key element in future FEL based light sources. ... more A high repetition rate, MHz, electron source is a key element in future FEL based light sources. The Advanced Photo-injector Experiment (APEX) at Lawrence Berkeley National Laboratory (LBNL) consists of a high repetition rate 186 MHz (VHF-band) CW electron gun, 1 MHz UV laser source, a pulsed 30 MeV linac, and the diagnostic components necessary to quantify the gun’s performance. The gun design is based on well-established, conventional RF cavity design, with a couple notable exceptions. The basis for the selection of this technology, novel design features, fabrication techniques and measured cavity performance are presented.
Part of the Behind the Scenes series at Berkeley Lab, this video highlights the lab's mechani... more Part of the Behind the Scenes series at Berkeley Lab, this video highlights the lab's mechanical fabrication facility and its exceptional ability to produce unique tools essential to the lab's scientific mission. Through a combination of skilled craftsmanship and precision equipment, machinists and engineers work with scientists to create exactly what's needed - whether it's measured in microns or meters.
APEX2 is a proposed high repetition rate, high brightness electron source based on continuous-wav... more APEX2 is a proposed high repetition rate, high brightness electron source based on continuous-wave normal conducting RF cavities, aiming to further extend the brightness performance for Free Electron Laser and Ultra-fast Electron Diffraction/Ultra-fast Electron Microscopy beyond APEX. APEX2 photo-electron gun cavity consists of two 162.5 MHz RF cells, one Gun Cell for generating photoelectrons and one 2nd Cell for further accelerating the beam. Both cells adopt the re-entrant structure similar to APEX. In this paper, we present the RF design of the APEX2 cavity. A novel cavity design method based on Multi-Objective Genetic Algorithm has been implemented. A design that fulfills the requirements of both beam dynamics and engineering feasibility has been achieved.
The APEX electron source at LBNL combines highrepetition-rate and high beam brightness typical of... more The APEX electron source at LBNL combines highrepetition-rate and high beam brightness typical of photoguns, delivering low emittance electron pulses at MHz frequency. Proving the high beam quality of the beam is an essential step for the success of the experiment. It would enable high repetition rate operations for brightness-hungry applications such as X-Ray FELs, and MHz ultrafast electron diffraction. A full 6D characterization of the beam phase space at the gun beam energy (750 keV) is foreseen in the first phase of the project. Diagnostics for low and high current measurements have been installed and tested, measuring the performances of different cathode materials in a RF environment with mA average current. A double-slit system allows the characterization of beam emittance at high charge and full current (mA). An rf deflecting cavity is being installed, and a high precision spectrometer allow the characterization of the longitudinal phase space. Here we present the latest re...
STATUS OF THE APEX PROJECT AT LBNL* F. Sannibale, B. Bailey, K. Baptiste, J. Byrd, C. Cork, J. Co... more STATUS OF THE APEX PROJECT AT LBNL* F. Sannibale, B. Bailey, K. Baptiste, J. Byrd, C. Cork, J. Corlett, S. De Santis, S. Dimaggio, L. Doolittle, J. Doyle, P. Emma, J. Feng, D. Filippetto, D. Garcia Quintas, G. Huang, H. Huang, T. Kramasz, S. Kwiatkoswski, W.E. Norum, H. Padmore, C.F. Papadopoulos, C. Pappas, G. Portmann, J. Qiang, J. Staples, T. Vecchione, M. Venturini, M. Vinco, W. Wan, R. Wells, M. Zolotorev, F. Zucca, LBNL, Berkeley, CA, USA M. Prantil, M. Messerly, LLNL, Livermore, CA, USA C. Pogue, Naval Postgraduate School, Monterey, CA, USA Abstract The Advanced Photo-injector Experiment (APEX) at the Lawrence Berkeley National Laboratory is focused on the development of a high-brightness high-repetition rate (MHz-class) electron injector for X-ray FEL applications. The injector is based on a new concept gun, utilizing a normal conducting 186 MHz RF cavity operating in CW mode in conjunction with high quantum efficiency photocathodes capable of delivering the required repetit...
Science needs in the last decade have been pushing the accelerator community to the development o... more Science needs in the last decade have been pushing the accelerator community to the development of high repetition rates (MHz/GHz-class) linac-based schemes capable of generating high brightness electron beams. Examples include X-ray FELs; ERLs for light sources, electron cooling and IR to EUV FEL applications; inverse Compton scattering X-ray or gamma sources; and ultrafast electron diffraction and microscopy. The high repetition rate requirement has profound implications on the technology choice for most of the accelerator parts, and in particular for the electron gun. The successful performance of the GHz room-temperature RF photoinjectors running at rates <~100 Hz, cannot be scaled up to higher rates because of the excessive heat load that those regimes would generate on the gun cavity walls. In response to this gun need, we have developed at the Berkeley Lab the VHF-Gun, a lower-frequency roomtemperature RF photo-gun capable of CW operation and optimized for the performance ...
APEX2 is a proposed normal conducting radio-frequency (RF) electron gun operating in the very hig... more APEX2 is a proposed normal conducting radio-frequency (RF) electron gun operating in the very high frequency (VHF) range in continuous wave (CW) mode, designed to drive applications that require both high beam brightness and high repetition rate, such as free electron lasers (such as LCLS-II-HE), ultra-fast electron diffraction, and microscopy. The gun consists of a two-cell RF cavity operating at 162.5 MHz with a cathode field of 34 MV/m, together with an embedded focusing solenoid. We study the beam dynamics in an APEX2-based photoinjector (up to 20 MeV), targeting a transverse 95% beam emittance of 0.1 μm at 12.5 A peak current for the case of 100 pC charge for FEL applications. The high cathode field leads to enhanced beam brightness, while the increased gun exit energy of 1.5 MeV reduces the effects of space charge, and possibly eliminates the need for an RF buncher. The embedded solenoid is designed to control the transverse beam size while minimizing emittance growth due to g...
The design of a 1.3 GHz buncher cavity for the APEX project, a MHz repetition rate high-brightnes... more The design of a 1.3 GHz buncher cavity for the APEX project, a MHz repetition rate high-brightness photoinjector, is presented. The buncher cavity operates at 240 kV in CW mode, and it compresses the 750 keV beam from APEX gun through ballistic compression. Compared with a single cell design, a two-cell cavity doubles the shunt impedance to 7.8 M� , which greatly relaxes the requirements for both RF amplifier and cavity cooling. Coupler design, multipacting analysis, HOM analysis and thermal analysis will be presented in this paper.
The Advanced Photoinjector Experiment is a photoinjector project at Lawrence Berkeley National La... more The Advanced Photoinjector Experiment is a photoinjector project at Lawrence Berkeley National Lab, designed to test the performance of a high repetition rate (1 MHz) VHF normal conducting electron gun. The requirements of high beam brightness, as well as significant compression at low energy determine the base setup for the injector transport line. The beam dynamics considerations for a high repetition rate injector are discussed and the potential to use multiple bunch charges that require different tunings of the base setup is explored.
Thu [cpoil wit prtpiirJ ii m tumini nl «"n\ tpmii'ttd by Ihe llrn'ri SU1«* (rimnnwil Nclta ifif U... more Thu [cpoil wit prtpiirJ ii m tumini nl «"n\ tpmii'ttd by Ihe llrn'ri SU1«* (rimnnwil Nclta ifif United Shin nut iht Urtiift) Sisw tixifY RcifUili inJ Dt'clDpmtn! Admmiiiralwn, nut irr " (hcu cmplnyw, nor iiiy nl ihfif rohUiCIMi ml tonlnKlttn ut iheii rtnplufKi. nukti any wiirjniy, «»P'«i "i implird, 01 luuiriti jn» lejal lull ill [^ HI iriptiiiiiliiUiy f. n I tit muii(>. ? umplelencu Oi iivfulncq ql my ntftirnutiun. jppiulm, pjodurt 01 piwn dikl.iKd. ni Kpintnn (hil in uu would nm inlnnp pnu'dl HWTKJ ti|hu.
A new porcelain-enamel coated antenna creates a clean plasma for volume or surface-conversion ion... more A new porcelain-enamel coated antenna creates a clean plasma for volume or surface-conversion ion sources. The porcelain-enamel coating is hard, electrically insulating, long lasting, non fragile, and resistant to puncture by high energy ions in the plasma. Plasma and ion production using the porcelain enamel coated antenna is uncontaminated with filament or extraneous metal ion because the porcelain does not
Currently proposed ERL and high average power FEL projects require electron beam sources that can... more Currently proposed ERL and high average power FEL projects require electron beam sources that can generate â1nC bunch charges at high repetition rates. Many proposed sources are based around either high voltage DC or microwave RF guns, each with its particular set of technological limits and system complications. We propose a novel solution that greatly diminishes high voltage breakdown issues
Advances in X-ray Free-Electron Lasers Instrumentation III, 2015
After the formidable results of X-ray 4th generation light sources based on free electron lasers ... more After the formidable results of X-ray 4th generation light sources based on free electron lasers around the world, a new revolutionary step is undergoing to extend the FEL performance from the present few hundred Hz to MHz-class repetition rates. In such facilities, temporally equi-spaced pulses will allow for a wide range of previously non-accessible experiments. The Advanced Photo-injector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL), is devoted to test the capability of a novel scheme electron source, the VHF-Gun, to generate the required electron beam brightness at MHz repetition rates. In linac-based FELs, the ultimate performance in terms of brightness is defined at the injector, and in particular, cathodes play a major role in the game. Part of the APEX program consists in testing high quantum efficiency photocathodes capable to operate at the conditions required by such challenging machines. Results and status of these tests at LBNL are presented.
Proceedings of the 2003 Bipolar/BiCMOS Circuits and Technology Meeting (IEEE Cat. No.03CH37440)
The vacuum system for a proposed 2.5 GeV, 10µA recirculating linac synchrotron light source [1] i... more The vacuum system for a proposed 2.5 GeV, 10µA recirculating linac synchrotron light source [1] is readily achievable with conventional vacuum hardware and established fabrication processes. Some of the difficult technical challenges associated with synchrotron light source storage rings are sidestepped by the relatively low beam current and short beam lifetime requirements of a re-circulating linac. This minimal lifetime requirement leads directly to relatively high limits on the background gas pressure through much of the facility. The 10µA average beam current produces very little synchrotron radiation induced gas desorption and thus the need for an "ante-chamber" in the vacuum chamber is eliminated. In the arc bend magnets, and the insertion devices, the vacuum chamber dimensions can be selected to balance the coherent synchrotron radiation and resistive wall wakefield effects, while maintaining the modest limits on the gas pressure and minimal outgassing.
Recent reports have identified the scientific requirements for a future soft x-ray light source a... more Recent reports have identified the scientific requirements for a future soft x-ray light source and a high-repetition-rate FEL facility responsive to them is being studied at LBNL. The facility is based on a CW superconducting linear accelerator with beam supplied by a high-brightness, high-repetition-rate photocathode electron gun, and on an array of FELs to which the beam is distributed, each operating at high repetition rate and with even pulse spacing. Dependent on the experimental requirements, the individual FELs may be configured for either SASE, HGHG, EEHG, or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format ranging from sub-femtoseconds to hundreds of femtoseconds. We are developing a design concept for a 10-beamline, coherent, soft x-ray FEL array powered by a 2.5 GeV superconducting accelerator operating with a 1 MHz bunch repetition rate. Electron bunches are fanned out through a spreader, distributing be...
We report recent progress on the design of a normal conducting CW electron gun, APEX-II (Advanced... more We report recent progress on the design of a normal conducting CW electron gun, APEX-II (Advanced Photo-injector EXperiment-II) at Lawrence Berkeley National Laboratory. APEX-II is an upgrade of the successful APEX gun and the LCLS-II (Linac Coherent Light Source-II) injector, aiming at applications for Free electron laser (FEL) such as LCLS-II High Energy upgrade, UED (Ultrafast Electron Diffraction) and UEM (Ultrafast Electron Microscopy). The APEX-II adopted a two-cell cavity design with resonant frequency of 162.5 MHz. The APEX-II gun is targeting to achieve exceeding 30 MV/m of launch gradient at the cathode and output energy above 1.5 MeV with transverse emittance of 0.1 um at 100 pC. Advanced MOGA optimization technique has been used for both the RF cavity design and extensive beam dynamics studies using APEX-like and LCLS-II like injector layout. Detailed RF designs, beam dynamics studies, preliminary engineering design and FEA analysis will be presented, with cavity feature...
The Advanced Photo-injector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL)... more The Advanced Photo-injector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL) is dedicated to the demonstration of the capability of an electron injector based on the VHF-gun, the new concept RF gun developed at LBNL, of delivering the beam quality required by MHz-class repetition rate X-Ray free electron lasers. Project status, plans, and recent results are presented.
A high repetition rate, MHz, electron source is a key element in future FEL based light sources. ... more A high repetition rate, MHz, electron source is a key element in future FEL based light sources. The Advanced Photo-injector Experiment (APEX) at Lawrence Berkeley National Laboratory (LBNL) consists of a high repetition rate 186 MHz (VHF-band) CW electron gun, 1 MHz UV laser source, a pulsed 30 MeV linac, and the diagnostic components necessary to quantify the gun’s performance. The gun design is based on well-established, conventional RF cavity design, with a couple notable exceptions. The basis for the selection of this technology, novel design features, fabrication techniques and measured cavity performance are presented.
Part of the Behind the Scenes series at Berkeley Lab, this video highlights the lab's mechani... more Part of the Behind the Scenes series at Berkeley Lab, this video highlights the lab's mechanical fabrication facility and its exceptional ability to produce unique tools essential to the lab's scientific mission. Through a combination of skilled craftsmanship and precision equipment, machinists and engineers work with scientists to create exactly what's needed - whether it's measured in microns or meters.
APEX2 is a proposed high repetition rate, high brightness electron source based on continuous-wav... more APEX2 is a proposed high repetition rate, high brightness electron source based on continuous-wave normal conducting RF cavities, aiming to further extend the brightness performance for Free Electron Laser and Ultra-fast Electron Diffraction/Ultra-fast Electron Microscopy beyond APEX. APEX2 photo-electron gun cavity consists of two 162.5 MHz RF cells, one Gun Cell for generating photoelectrons and one 2nd Cell for further accelerating the beam. Both cells adopt the re-entrant structure similar to APEX. In this paper, we present the RF design of the APEX2 cavity. A novel cavity design method based on Multi-Objective Genetic Algorithm has been implemented. A design that fulfills the requirements of both beam dynamics and engineering feasibility has been achieved.
The APEX electron source at LBNL combines highrepetition-rate and high beam brightness typical of... more The APEX electron source at LBNL combines highrepetition-rate and high beam brightness typical of photoguns, delivering low emittance electron pulses at MHz frequency. Proving the high beam quality of the beam is an essential step for the success of the experiment. It would enable high repetition rate operations for brightness-hungry applications such as X-Ray FELs, and MHz ultrafast electron diffraction. A full 6D characterization of the beam phase space at the gun beam energy (750 keV) is foreseen in the first phase of the project. Diagnostics for low and high current measurements have been installed and tested, measuring the performances of different cathode materials in a RF environment with mA average current. A double-slit system allows the characterization of beam emittance at high charge and full current (mA). An rf deflecting cavity is being installed, and a high precision spectrometer allow the characterization of the longitudinal phase space. Here we present the latest re...
STATUS OF THE APEX PROJECT AT LBNL* F. Sannibale, B. Bailey, K. Baptiste, J. Byrd, C. Cork, J. Co... more STATUS OF THE APEX PROJECT AT LBNL* F. Sannibale, B. Bailey, K. Baptiste, J. Byrd, C. Cork, J. Corlett, S. De Santis, S. Dimaggio, L. Doolittle, J. Doyle, P. Emma, J. Feng, D. Filippetto, D. Garcia Quintas, G. Huang, H. Huang, T. Kramasz, S. Kwiatkoswski, W.E. Norum, H. Padmore, C.F. Papadopoulos, C. Pappas, G. Portmann, J. Qiang, J. Staples, T. Vecchione, M. Venturini, M. Vinco, W. Wan, R. Wells, M. Zolotorev, F. Zucca, LBNL, Berkeley, CA, USA M. Prantil, M. Messerly, LLNL, Livermore, CA, USA C. Pogue, Naval Postgraduate School, Monterey, CA, USA Abstract The Advanced Photo-injector Experiment (APEX) at the Lawrence Berkeley National Laboratory is focused on the development of a high-brightness high-repetition rate (MHz-class) electron injector for X-ray FEL applications. The injector is based on a new concept gun, utilizing a normal conducting 186 MHz RF cavity operating in CW mode in conjunction with high quantum efficiency photocathodes capable of delivering the required repetit...
Science needs in the last decade have been pushing the accelerator community to the development o... more Science needs in the last decade have been pushing the accelerator community to the development of high repetition rates (MHz/GHz-class) linac-based schemes capable of generating high brightness electron beams. Examples include X-ray FELs; ERLs for light sources, electron cooling and IR to EUV FEL applications; inverse Compton scattering X-ray or gamma sources; and ultrafast electron diffraction and microscopy. The high repetition rate requirement has profound implications on the technology choice for most of the accelerator parts, and in particular for the electron gun. The successful performance of the GHz room-temperature RF photoinjectors running at rates <~100 Hz, cannot be scaled up to higher rates because of the excessive heat load that those regimes would generate on the gun cavity walls. In response to this gun need, we have developed at the Berkeley Lab the VHF-Gun, a lower-frequency roomtemperature RF photo-gun capable of CW operation and optimized for the performance ...
APEX2 is a proposed normal conducting radio-frequency (RF) electron gun operating in the very hig... more APEX2 is a proposed normal conducting radio-frequency (RF) electron gun operating in the very high frequency (VHF) range in continuous wave (CW) mode, designed to drive applications that require both high beam brightness and high repetition rate, such as free electron lasers (such as LCLS-II-HE), ultra-fast electron diffraction, and microscopy. The gun consists of a two-cell RF cavity operating at 162.5 MHz with a cathode field of 34 MV/m, together with an embedded focusing solenoid. We study the beam dynamics in an APEX2-based photoinjector (up to 20 MeV), targeting a transverse 95% beam emittance of 0.1 μm at 12.5 A peak current for the case of 100 pC charge for FEL applications. The high cathode field leads to enhanced beam brightness, while the increased gun exit energy of 1.5 MeV reduces the effects of space charge, and possibly eliminates the need for an RF buncher. The embedded solenoid is designed to control the transverse beam size while minimizing emittance growth due to g...
The design of a 1.3 GHz buncher cavity for the APEX project, a MHz repetition rate high-brightnes... more The design of a 1.3 GHz buncher cavity for the APEX project, a MHz repetition rate high-brightness photoinjector, is presented. The buncher cavity operates at 240 kV in CW mode, and it compresses the 750 keV beam from APEX gun through ballistic compression. Compared with a single cell design, a two-cell cavity doubles the shunt impedance to 7.8 M� , which greatly relaxes the requirements for both RF amplifier and cavity cooling. Coupler design, multipacting analysis, HOM analysis and thermal analysis will be presented in this paper.
The Advanced Photoinjector Experiment is a photoinjector project at Lawrence Berkeley National La... more The Advanced Photoinjector Experiment is a photoinjector project at Lawrence Berkeley National Lab, designed to test the performance of a high repetition rate (1 MHz) VHF normal conducting electron gun. The requirements of high beam brightness, as well as significant compression at low energy determine the base setup for the injector transport line. The beam dynamics considerations for a high repetition rate injector are discussed and the potential to use multiple bunch charges that require different tunings of the base setup is explored.
Thu [cpoil wit prtpiirJ ii m tumini nl «"n\ tpmii'ttd by Ihe llrn'ri SU1«* (rimnnwil Nclta ifif U... more Thu [cpoil wit prtpiirJ ii m tumini nl «"n\ tpmii'ttd by Ihe llrn'ri SU1«* (rimnnwil Nclta ifif United Shin nut iht Urtiift) Sisw tixifY RcifUili inJ Dt'clDpmtn! Admmiiiralwn, nut irr " (hcu cmplnyw, nor iiiy nl ihfif rohUiCIMi ml tonlnKlttn ut iheii rtnplufKi. nukti any wiirjniy, «»P'«i "i implird, 01 luuiriti jn» lejal lull ill [^ HI iriptiiiiiliiUiy f. n I tit muii(>. ? umplelencu Oi iivfulncq ql my ntftirnutiun. jppiulm, pjodurt 01 piwn dikl.iKd. ni Kpintnn (hil in uu would nm inlnnp pnu'dl HWTKJ ti|hu.
A new porcelain-enamel coated antenna creates a clean plasma for volume or surface-conversion ion... more A new porcelain-enamel coated antenna creates a clean plasma for volume or surface-conversion ion sources. The porcelain-enamel coating is hard, electrically insulating, long lasting, non fragile, and resistant to puncture by high energy ions in the plasma. Plasma and ion production using the porcelain enamel coated antenna is uncontaminated with filament or extraneous metal ion because the porcelain does not
Currently proposed ERL and high average power FEL projects require electron beam sources that can... more Currently proposed ERL and high average power FEL projects require electron beam sources that can generate â1nC bunch charges at high repetition rates. Many proposed sources are based around either high voltage DC or microwave RF guns, each with its particular set of technological limits and system complications. We propose a novel solution that greatly diminishes high voltage breakdown issues
Advances in X-ray Free-Electron Lasers Instrumentation III, 2015
After the formidable results of X-ray 4th generation light sources based on free electron lasers ... more After the formidable results of X-ray 4th generation light sources based on free electron lasers around the world, a new revolutionary step is undergoing to extend the FEL performance from the present few hundred Hz to MHz-class repetition rates. In such facilities, temporally equi-spaced pulses will allow for a wide range of previously non-accessible experiments. The Advanced Photo-injector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL), is devoted to test the capability of a novel scheme electron source, the VHF-Gun, to generate the required electron beam brightness at MHz repetition rates. In linac-based FELs, the ultimate performance in terms of brightness is defined at the injector, and in particular, cathodes play a major role in the game. Part of the APEX program consists in testing high quantum efficiency photocathodes capable to operate at the conditions required by such challenging machines. Results and status of these tests at LBNL are presented.
Proceedings of the 2003 Bipolar/BiCMOS Circuits and Technology Meeting (IEEE Cat. No.03CH37440)
The vacuum system for a proposed 2.5 GeV, 10µA recirculating linac synchrotron light source [1] i... more The vacuum system for a proposed 2.5 GeV, 10µA recirculating linac synchrotron light source [1] is readily achievable with conventional vacuum hardware and established fabrication processes. Some of the difficult technical challenges associated with synchrotron light source storage rings are sidestepped by the relatively low beam current and short beam lifetime requirements of a re-circulating linac. This minimal lifetime requirement leads directly to relatively high limits on the background gas pressure through much of the facility. The 10µA average beam current produces very little synchrotron radiation induced gas desorption and thus the need for an "ante-chamber" in the vacuum chamber is eliminated. In the arc bend magnets, and the insertion devices, the vacuum chamber dimensions can be selected to balance the coherent synchrotron radiation and resistive wall wakefield effects, while maintaining the modest limits on the gas pressure and minimal outgassing.
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Papers by Russell Wells