Hyeri Lee

Cold electron beams from cryocooled, alkali antimonide photocathodes

In this paper we report on the generation of cold electron beams using a

Review and demonstration of ultra-low-emittance photocathode measurements

{\mathrm{Cs}}_{3}\mathrm{Sb}

Alkali antimonides photocathodes growth using pure metals evaporation from effusion cells

photocathode grown by codeposition of Sb and Cs. By cooling the photocathode to 90 K we demonstrate a significant reduction in the mean transverse energy validating the long-standing speculation that the lattice temperature contributes to limiting the mean transverse energy or intrinsic emittance near the photoemission threshold, opening new frontiers in generating ultrabright beams. At 90 K, we achieve a record low intrinsic emittance of

Ultra low emittance electron beams from multi-alkali antimonide photocathode operated with infrared light

0.2\text{ }\text{ }\ensuremath{\mu}\mathrm{m}

Rb based alkali antimonide high quantum efficiency photocathodes for bright electron beam sources and photon detection applications

(rms) per mm of laser spot diameter from an ultrafast (subpicosecond) photocathode with quantum efficiency greater than

A cryogenically cooled high voltage DC photoemission electron source

7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}

Demonstration of low emittance in the Cornell energy recovery linac injector prototype

using a visible laser wavelength of 690 nm.

Adaptive electron beam shaping using a photoemission gun and spatial light modulator

This paper reports the development of a simple and reliable apparatus for measuring ultra-low emittance, or equivalently the mean transverse energy from cryogenically cooled photocathodes. The existing methods to measure ultra-low emittance from photocathodes are reviewed. Inspired by the available techniques, we have implemented two complementary methods, the waist scan and voltage scan, in one system giving consistent results. Additionally, this system is capable of measuring the emittance at electric fields comparable to those obtained in DC photoinjectors.

Intrinsic emittance reduction in transmission mode photocathodes

The authors report on the growth of Na2KSb bialkali and Na2KSb:Cs3Sb multialkali photocathodes using the vapors generated by evaporating pure metals with effusion cells under vacuum conditions. Details about the ultrahigh vacuum growth system and the used procedures are provided. The new growth system is capable of growing over large areas with uniform photoemission properties using different types of substrates. The measured spectral response curves indicate that high quality photocathodes are produced with peak quantum efficiencies well above 20%. Procedures to obtain multialkali photocathodes with extended sensitivity into the infrared range (well above 800 nm) are described.

Erratum: “Intrinsic emittance reduction in transmission mode photocathodes” [Appl. Phys. Lett. 108, 124105 (2016)]

The intrinsic emittance of electron beams generated from a multi-alkali photocathode operated in a high voltage DC gun is reported. The photocathode showed sensitivity extending to the infrared part of the spectrum up to 830 nm. The measured intrinsic emittances of electron beams generated with light having wavelength longer than 800 nm are approaching the limit imposed by the thermal energy of electrons at room temperature with quantum efficiencies comparable to metallic photocathodes used in operation of modern photoinjectors.