Thermal emittance measurements of a cesium potassium antimonide photocathode

Bazarov, Ivan; Cultrera, L.; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Li, Yulin; Liu, Xianghong; Maxson, Jared; Roussel, William

doi:10.1063/1.3596450

Cited by 74 publications

(71 citation statements)

References 5 publications

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“…A cathode intrinsic emittance of 0.5-0.6 μm per mm rms was measured in the gun over several cathodes at 532 nm. This measurement agrees well with the previous intrinsic emittance measurements of K-Cs-Sb cathodes in dc guns [14]. No evidence of QE depletion in the cathode central area due to ion back-bombardment or heating or sputtering induced by the laser used for inducing photoemission from the cathode was found.…”

Section: B Photocathode Performancesupporting

confidence: 81%

Temperature-dependent quantum efficiency degradation of K-Cs-Sb bialkali antimonide photocathodes grown by a triple-element codeposition method

Ding

Karkare

Feng

et al. 2017

Phys. Rev. Accel. Beams

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K-Cs-Sb bialkali antimonide photocathodes grown by a triple-element codeposition method have been found to have excellent quantum efficiency (QE) and outstanding near-atomic surface smoothness and have been employed in the VHF gun in the Advanced Photoinjector Experiment (APEX), however, their robustness in terms of their lifetime at elevated photocathode temperature has not yet been investigated. In this paper, the relationship between the lifetime of the K-Cs-Sb photocathode and the photocathode temperature has been investigated. The origin of the significant QE degradation at photocathode temperatures over 70°C has been identified as the loss of cesium atoms from the K-Cs-Sb photocathode, based on the in situ x-ray analysis on the photocathode film during the decay process. The findings from this work will not only further the understanding of the behavior of K-Cs-Sb photocathodes at elevated temperature and help develop more temperature-robust cathodes, but also will become an important guide to the design and operation of the future high-field rf guns employing the use of such photocathodes.

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Section: B Photocathode Performancesupporting

confidence: 81%

Temperature-dependent quantum efficiency degradation of K-Cs-Sb bialkali antimonide photocathodes grown by a triple-element codeposition method

Ding

Karkare

Feng

et al. 2017

Phys. Rev. Accel. Beams

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“…[14]. Other groups report higher QE at 532 nm, of the order of 8% [2,3], suggesting our growth procedure is not optimized.…”

Section: Experiments a Photocathode Preparationmentioning

confidence: 98%

“…15(b), was found to be 0:73 AE 0:06 mm mrad=mmðrmsÞ at 532 nm. We did not intend to perform a rigorous thermal emittance measurement; however our normalized rms emittance per laser size values is reasonable considering previously reported thermal emittance values [2]. Emittance measurements are summarized in Table II.…”

Section: F Emittance Measurementsmentioning

confidence: 99%

“…The QE was relatively stable at 10 mA beam current and for current >16 mA the QE decreased [ Fig. 10 and the QE was observed to decay more slowly at currents between 15 and 20 mA, corresponding to 17 and 23 mA=mm 2 [ Fig. 10(b)].…”

Section: B Charge Lifetime At 440 Nm Very Good; Charge Lifetime At 5mentioning

confidence: 99%

“…Consistent results depend on adherence to proper growth procedures. The K 2 CsSb photocathode has a slightly larger thermal emittance [2] compared to GaAs but it is considered to be a prompt emitter because of its positive-electron affinity (PEA) nature, producing shorter bunches than GaAs. The biggest advantage however is the photocathode's ability to survive under markedly harsher vacuum conditions compared to GaAs [3].…”

Section: Introductionmentioning

confidence: 99%

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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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Novel Ultrabright and Air‐Stable Photocathodes Discovered from Machine Learning and Density Functional Theory Driven Screening

et al. 2021

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The high brightness, low emittance electron beams achieved in modern X‐ray free‐electron lasers (XFELs) have enabled powerful X‐ray imaging tools, allowing molecular systems to be imaged at picosecond time scales and sub‐nanometer length scales. One of the most promising directions for increasing the brightness of XFELs is through the development of novel photocathode materials. Whereas past efforts aimed at discovering photocathode materials have typically employed trial‐and‐error‐based iterative approaches, this work represents the first data‐driven screening for high brightness photocathode materials. Through screening over 74 000 semiconducting materials, a vast photocathode dataset is generated, resulting in statistically meaningful insights into the nature of high brightness photocathode materials. This screening results in a diverse list of photocathode materials that exhibit intrinsic emittances that are up to 4x lower than currently used photocathodes. In a second effort, multiobjective screening is employed to identify the family of M2O (M = Na, K, Rb) that exhibits photoemission properties that are comparable to the current state‐of‐the‐art photocathode materials, but with superior air stability. This family represents perhaps the first intrinsically bright, visible light photocathode materials that are resistant to reactions with oxygen, allowing for their transport and storage in dry air environments.

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Thermal emittance measurements of a cesium potassium antimonide photocathode

Cited by 74 publications

References 5 publications

Temperature-dependent quantum efficiency degradation of K-Cs-Sb bialkali antimonide photocathodes grown by a triple-element codeposition method

Temperature-dependent quantum efficiency degradation of K-Cs-Sb bialkali antimonide photocathodes grown by a triple-element codeposition method

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

Novel Ultrabright and Air‐Stable Photocathodes Discovered from Machine Learning and Density Functional Theory Driven Screening

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