The polarized electron source at NIKHEF

Putte, M.J.J. van den; Jager, C. W. de; Konstantinov, S. G.; Korchagin, V. Ya.; Kroes, F.; Leeuwen, E.P. van; Militsyn, Boris; Papadakis, Nicolas; Popov, S. G.; Serdobintsev, G. V.; Shatunov, Yu. M.; Shevelev, S.V.; Sluijk, T.; Терехов, А. С.; Tokarev, Yu. F.

doi:10.1063/1.55027

Cited by 8 publications

(8 citation statements)

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“…An inverted gun design [16] reduces the amount of metal biased at high voltage, and if field emission occurs, the electrons are less likely to strike the insulator due to the orientation of the electrostatic field lines. Segmented insulators [9] successfully shield the insulator from field emission and a recent demonstration indicates successful operation at 500 kV [17]. Field emission coatings [18] once seemed promising but unfortunately, serve to trap gas which is liberated during high voltage processing.…”

Section: Introductionmentioning

confidence: 99%

“…Some applications require high bunch charge [2] or small beam emittance [3] and for these circumstances it is beneficial to operate the photogun at very high bias voltage ($ 500 kV) and high field strength (> 10 MV=m) to produce a relativistic beam insensitive to space charge forces that degrade beam quality. The first DC high voltage photogun used at an accelerator operated at 100 kV [4] and many photoguns operating near this voltage were constructed shortly afterwards [5][6][7][8][9][10]. The Jefferson Lab Free Electron Laser employed the first photogun to operate at significantly higher voltage, $320 kV [11].…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of niobium as candidate electrode material for dc high voltage photoelectron guns

BastaniNejad

Mohamed

Elmustafa

et al. 2012

Phys. Rev. ST Accel. Beams

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The field emission characteristics of niobium electrodes were compared to those of stainless steel electrodes using a DC high voltage field emission test apparatus. A total of eight electrodes were evaluated: two 304 stainless steel electrodes polished to mirrorlike finish with diamond grit and six niobium electrodes (two single-crystal, two large-grain, and two fine-grain) that were chemically polished using a buffered-chemical acid solution. Upon the first application of high voltage, the best large-grain and single-crystal niobium electrodes performed better than the best stainless steel electrodes, exhibiting less field emission at comparable voltage and field strength. In all cases, field emission from electrodes (stainless steel and/or niobium) could be significantly reduced and sometimes completely eliminated, by introducing krypton gas into the vacuum chamber while the electrode was biased at high voltage. Of all the electrodes tested, a large-grain niobium electrode performed the best, exhibiting no measurable field emission (< 10 pA) at 225 kV with 20 mm cathode/anode gap, corresponding to a field strength of 18:7 MV=m.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of niobium as candidate electrode material for dc high voltage photoelectron guns

BastaniNejad

Mohamed

Elmustafa

et al. 2012

Phys. Rev. ST Accel. Beams

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show abstract

“…The basis for these introductory comments stems from reports of accelerator operation at a handful of locations [4][5][6][7][8]. Notably, the Jefferson Lab (JLab) free electron laser (FEL) employs GaAs inside a dc high voltage photogun biased at 350 kV and routinely operates at 5 mA average current [8], although occasional high voltage discharges sometimes necessitate time consuming photocathode replacement.…”

Section: Introductionmentioning

confidence: 99%

Charge lifetime measurements at high average current using aK2CsSbphotocathode inside a dc high voltage photogun

Mammei

Suleiman

Feingold

et al. 2013

Phys. Rev. ST Accel. Beams

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Two K 2 CsSb photocathodes were manufactured at Brookhaven National Lab and delivered to Jefferson Lab within a compact vacuum apparatus at pressure $10 À11 Torr. These photocathodes were evaluated using a dc high voltage photogun biased at voltages up to 200 kV, and illuminated with laser light at wavelengths 440 or 532 nm, to generate dc electron beams at currents up to 20 mA. Some conditions produced exceptionally large photocathode charge lifetimes, without measurable quantum efficiency decay, even from the center of the photocathode where operation using GaAs photocathodes is precluded due to ion bombardment. Under other conditions the charge lifetime was poor due to extensive ion bombardment under severely degraded vacuum conditions, and as a result of localized heating via the laser beam. Following beam delivery, the photocathodes were evaluated using a scanning electron microscope to determine surface morphology.

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“…The Jefferson Lab (JLab) inverted DC gun [2] has generated high average current in mA class with couple pC bunch charge while the SLC DC gun [3] has generated 10 nC with several μA's. Other labs such as MAMI [4], MIT-BATE [5], Bonn-ELSA [6] or NIKHEF [7] also tested and operated the polarized electron sources, but their results are less than the JLab and SLC results. However, none of them demonstrated high bunch charge (>100pC) and high average current (>1mA) simultaneously.…”

Section: The Hv DC Photo-gunmentioning

confidence: 99%

Conceptual design of a Polarized Electron Ion Collider at Brookhaven National Laboratory

Skaritka¹,

Wang²,

Willeke³

et al. 2018

Proceedings of XVII International Workshop on Polarized Sources, Targets &Amp; Polarimetry — PoS(PSTP2017)

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The polarized electron source at NIKHEF

Cited by 8 publications

References 0 publications

Evaluation of niobium as candidate electrode material for dc high voltage photoelectron guns

Evaluation of niobium as candidate electrode material for dc high voltage photoelectron guns

Charge lifetime measurements at high average current using aK2CsSbphotocathode inside a dc high voltage photogun

Conceptual design of a Polarized Electron Ion Collider at Brookhaven National Laboratory

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