Photocathodes for free electron lasers

Kong, Sunwoo; Kinross-Wright, J.; Nguyen, Dinh C.; Sheffield, R.L.

doi:10.1016/0168-9002(94)01425-6

Cited by 67 publications

(33 citation statements)

References 11 publications

(1 reference statement)

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“…[1,2]. For a representative RF accelerator operating at a few tens of GHz, an electron bunch just a few ps long is needed; therefore one must have a prompt switching response, for which the laserswitched photocathode is the preferred emitter.…”

Section: Photocathodes For Felsmentioning

confidence: 99%

Fabrication and measurement of efficient, robust cesiated dispenser photocathodes

Montgomery

Feldman

O'Shea

et al. 2007

2007 IEEE Particle Accelerator Conference (PAC)

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Photocathodes for high power free electron lasers face significant engineering and physics challenges in the quest for efficient, robust, long-lived, prompt laserswitched operation. The most efficient semiconductor photocathodes, notably those responsive to visible wavelengths, suffer from poor lifetime due to surface layer degradation, contamination, and desorption. Using a novel dispenser photocathode design, rejuvenation of cesiated surface layers in situ is investigated for semiconductor coatings building on previous results for cesiated metals. Cesium from a sub-surface reservoir diffuses to the surface through a microscopically porous, sintered tungsten matrix to repair the degraded surface layer. The goal of this research is to engineer and demonstrate efficient, robust, long-lived regenerable photocathodes in support of predictive photocathode modeling efforts and suitable for photoinjection applications.

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Section: Photocathodes For Felsmentioning

confidence: 99%

Fabrication and measurement of efficient, robust cesiated dispenser photocathodes

Montgomery

Feldman

O'Shea

et al. 2007

2007 IEEE Particle Accelerator Conference (PAC)

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“…Here we are not referring to the half-life, but to an operative definition of lifetime, which has more to do with ''usability'' in the FEL and with the concept of ''high'' QE already stated in the introduction and used by other authors. 4 Therefore, what we will consider as lifetime in the following discussion is the operation time after which the QE drops to a value close to 1%. This time was determined in this article only for MP cathodes, since they are the ones showing the best performances.…”

Section: A Lifetimementioning

confidence: 99%

“…1 For this reason, in past years, the electron accelerator and free electron laser ͑FEL͒ communities have been searching for a suitable material to be used as a photocathode in photoinjectors. [2][3][4] High (Ͼ1%) quantum efficiency ͑QE͒ for photoemission by visible or soft UV light and long lifetime under operating conditions are desired photocathode's features, difficult to be matched. Recently, we have demonstrated the photoemissive properties of K-Te semiconductor films evaporated under ultrahigh vacuum ͑UHV͒ conditions.…”

Section: Introductionmentioning

confidence: 99%

K–Te photocathodes: A new electron source for photoinjectors

Bisero¹,

Oerle²,

Ernst

et al. 1997

Journal of Applied Physics

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K-Te photocathodes deposited on a Mo substrate have been successfully used as an electron source in the free electron laser of University of Twente. Long lifetimes have been measured: after more than 20 h of operation in the accelerator a K-Te cathode with 4.75% initial quantum efficiency still displays a 1.1% quantum efficiency at 259 nm. Moreover, the quantum efficiency of this cathode versus operation time can be fitted by an exponential decay curve, which saturates asymptotically to a 1.03% value, suggesting that a quantum efficiency close to 1% could be sustained for very long operation times. Films degraded by use can be recovered to a quantum efficiency which is close to the initial value, by heating the substrate at temperatures between 100 and 330°C. A new procedure to obtain K-Te cathodes with high ͑up to 11%͒ quantum efficiencies is described.

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“…In the last years, the electron beam physics community has identified photocathodes as a key area of research needed to meet the challenges of next generation light sources, where in particular, electron beams with very high repetition rate and low emittance will be required. 1,2 Bi-Alkali antimonide cathodes are prime candidates for next generation photoinjectors and have been the subject of intense research activity, [3][4][5][6] but much about the materials science of these systems needs to be explored before they can be adopted as robust technologies. Here, we present results from a new tool for production and analysis of accelerator photocathodes.…”

mentioning

confidence: 99%

Direct observation of bi-alkali antimonide photocathodes growth via in operando x-ray diffraction studies

et al. 2014

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Alkali antimonides have a long history as visible-light-sensitive photocathodes. This work focuses on the process of fabrication of the bi-alkali photocathodes, K2CsSb. In-situ synchrotron x-ray diffraction and photoresponse measurements were used to monitor phase evolution during sequential photocathode growth mode on Si(100) substrates. The amorphous-to-crystalline transition for the initial antimony layer was observed at a film thickness of 40 Å . The antimony crystalline structure dissolved upon potassium deposition, eventually recrystallizing upon further deposition into K-Sb crystalline modifications. This transition, as well as the conversion of potassium antimonide to K2CsSb upon cesium deposition, is correlated with changes in the quantum efficiency.

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Photocathodes for free electron lasers

Cited by 67 publications

References 11 publications

Fabrication and measurement of efficient, robust cesiated dispenser photocathodes

Fabrication and measurement of efficient, robust cesiated dispenser photocathodes

K–Te photocathodes: A new electron source for photoinjectors

Direct observation of bi-alkali antimonide photocathodes growth via in operando x-ray diffraction studies

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