H<scp>IGH</scp>-C<scp>URRENT</scp>E<scp>NERGY</scp>-R<scp>ECOVERING</scp>E<scp>LECTRON</scp>L<scp>INACS</scp>

Merminga, L.; Douglas, D.; Krafft, Geoffrey

doi:10.1146/annurev.nucl.53.041002.110456

Cited by 49 publications

(31 citation statements)

References 47 publications

(33 reference statements)

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“…Thereafter, the (degraded) exhaust beam must be energy recovered. The latter task has been repeatedly and routinely demonstrated over a range of beam energies, currents, and powers [25] and the performance of the system described here does not deviate dramatically from previous designs.…”

Section: Electron Beam Transportmentioning

confidence: 74%

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A proposed VUV oscillator-based FEL upgrade at Jefferson Lab

Benson

Douglas

Evtushenko

et al. 2011

Journal of Modern Optics

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Advances in superconducting linac technology offer the possibility of an upgrade of the Jefferson Lab Free Electron Laser (JLab FEL) facility to an oscillator-based VUV-FEL that would produce 6 Â 10 12 coherent 100 eV photons per pulse at multi-MHz repetition rates in the fundamental. In this paper we present novel designs that are verified by model calculations which have themselves been validated by comparison with experimental performance measurements using oscillator-based continuous-wave free electron lasers (FELs) operating in the IR and UV, with sub-picosecond pulses up to 75 MHz and producing harmonics upwards of 10 eV. The accelerator uses an energy recovered linac design for efficiency of operation, and high gain per pass in the oscillator. The fully coherent nature of the source results in peak and average brightness values that are several orders of magnitude higher than storage rings.

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Section: Electron Beam Transportmentioning

confidence: 74%

“…Control of beam breakup has been demonstrated in recirculated SRF linacs and ERLs spanning a range of energies [25,30]. The modular recirculator design described above provides redundant control of transverse phase space and allows control of both turn-toturn phase advances and beam envelope functions.…”

Section: Electron Beam Transportmentioning

confidence: 99%

A proposed VUV oscillator-based FEL upgrade at Jefferson Lab

Benson

Douglas

Evtushenko

et al. 2011

Journal of Modern Optics

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“…The study of an Electron-Ion Collider (EIC) machine in Jefferson Lab as a future upgrade to CEBAF has been ongoing for many years. Initially, it was conceptualized as an Energy Recovery Linac (ERL) and ring scheme [15], but in 2006, a ring-ring concept was adopted on the grounds of luminosity optimization and minimization of technical risks. This machine was known as the Medium Energy Electron-Ion Collider.…”

Section: Jleic Conceptmentioning

confidence: 99%

Crab cavity requirements for the Jefferson Lab Electron-Ion Collider

Güitrón

2018

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An Electron-Ion Collider (EIC) has been proposed to be the next large facility to explore the dynamics of quarks and gluons inside nuclei. A conceptual design for a Jefferson Lab Electron-Ion Collider (JLEIC) is being developed. It is based on the CEBAF 12 GeV machine as a full energy electron beam injector. Two crucial requirements of JLEIC are high luminosity in the 10 34 cm −2 s −1 range, and full acceptance detection of particles. The full acceptance requirement relies on having the beams collide at a relatively large crossing angle of 50 mrad. Such a large crossing angle, however, can reduce the luminosity by as much as an order of magnitude. One way to compensate for geometric luminosity loss due to the beam crossing angle is using crab cavities. Crab cavities are superconducting radio-frequency structures optimized to produce a transverse force that "tilts" the beam bunches in such a way that a head-on collision is restored at the collision point, thus restoring the luminosity. A second set of crab cavities is placed downstream of the collision point and is used to cancel the initial bunch tilt, ideally suppressing any crab-induced effects anywhere else in the rings. in this project, and specially for his patience and financial support during my time at CAS.

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“…Initial investigations revealed that field emission initiates from electrode sites where the work function is lower, and microstructural defects such as grain boundaries often serve as the low work function regions on the electrode surface [19,25,26]. Inert gas conditioning of electrodes has been proven to eliminate field emission from cathode electrodes of DC high voltage photoelectron…”

Section: Elimination Of High Voltage Induced Field Emission From Elecmentioning

confidence: 99%

Thin film studies toward improving the performance of accelerator electron sources

Mamun

2016

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Future electron accelerators require DC high voltage photoguns to operate beyond the present state of the art to conduct new experiments that require ultra-bright electron beams with high average current and higher bunch charge. To meet these demands, the accelerators must demonstrate improvements in a number of photogun areas including vacuum, field emission elimination in high voltage electrodes, and photocathodes. This dissertation illustrates how these improvements can be achieved by the application of suitable thin-films to the photogun structure for producing ultra-bright electron beams.This work is composed of three complementary studies. First, the outgassing rates of three nominally identical 304L stainless steel vacuum chambers were studied to determine the effects of chamber coatings (silicon and titanium nitride) and heat treatments. For an uncoated stainless steel chamber, the diffusion limited outgassing was taken over by the recombination limited process as soon as a low outgassing rate of ~1.79(0.05)  10 -13 Torr L s -1 cm -2 was achieved. An amorphous silicon coating on the stainless steel chambers exhibited recombination limited behavior and any heat treatment became ineffective in reducing the outgassing rate. A TiN coated chamber yielded the smallest apparent outgassing rate of all the chambers: 6.44(0.05)  10 -13 Torr L s -1 cm -2 following an initial 90 °C bake and 2(20)  10 -16 Torr L s -1 cm -2 following the final bake in the series. This perceived low outgassing rate was attributed to the small pumping nature of TiN coating itself.Second, the high voltage performance of three TiN-coated aluminum electrodes, before and after gas conditioning with helium, were compared to that of bare aluminum electrodes and electrodes manufactured from titanium alloy (Ti-6Al-4V). This study suggests that aluminum electrodes, coated with TiN, could simplify the task of implementing photocathode cooling, which is required for future high current electron beam applications. The best performing TiNcoated aluminum electrode demonstrated less than 15 pA of field emission current at -175 kV for a 10 mm cathode/anode gap, which corresponds to a field strength of 22.5 MV/m. Third, the effect of antimony thickness on the performance of bialkali-antimonide photocathodes was studied. The high-capacity effusion source enabled us to successfully manufacture photocathodes having a maximum QE around 10% and extended low voltage 1/e lifetime (> 90 days) at 532 nm via the co-deposition method, with relatively thick layers of antimony (≥ 300 nm). We speculate that alkali co-deposition provides optimized stoichiometry for photocathodes manufactured using thick Sb layers, which could serve as a reservoir for the alkali.In summary, this research examined the effectiveness of thin films applied on photogun chamber components to achieve an extremely high vacuum, to eliminate high voltage induced field emission from electrodes, and to generate photocurrent with high quantum yield with an extended operational lifetime. Simult...

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HIGH-CURRENTENERGY-RECOVERINGELECTRONLINACS

Cited by 49 publications

References 47 publications

A proposed VUV oscillator-based FEL upgrade at Jefferson Lab

A proposed VUV oscillator-based FEL upgrade at Jefferson Lab

Crab cavity requirements for the Jefferson Lab Electron-Ion Collider

Thin film studies toward improving the performance of accelerator electron sources

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