Intrinsic Emittance Reduction of an Electron Beam from Metal Photocathodes

Journal Article · Fri Jun 11 04:00:00 EDT 2010 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.104.234802· OSTI ID:21410403

Hauri, C P; Ganter, R; Le Pimpec, F; Trisorio, A; Ruchert, C; Braun, H H ^[1]

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1. Paul Scherrer Institute, 5232 Villigen (Switzerland)

Electron beams in modern linear accelerators are now becoming limited in brightness by the intrinsic emittance of the photocathode electron source. Therefore it becomes important for large scale facilities such as free electron lasers to reduce this fundamental limit. In this Letter we present measurements of the intrinsic emittance for different laser wavelength (from 261 to 282 nm) and for different photocathode materials such as Mo, Nb, Al, Cu. Values as low as 0.41{+-}0.03 mm{center_dot}mrad/mm laser spot size (rms) were measured for a copper photocathode illuminated with a 282 nm laser wavelength. The key element for emittance reduction is a uv laser system which allows adjustment of the laser photon energy to match the effective work function of the cathode material and to emit photoelectrons with a lower initial kinetic energy. The quantum efficiency over the explored wavelength range varies by less than a factor of 3.

• OSTI ID: 21410403
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 23 Vol. 104; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ACCELERATORS
BEAM EMITTANCE
BEAMS
BOSONS
BRIGHTNESS
CATHODES
COPPER
EFFICIENCY
ELECTRODES
ELECTRON BEAMS
ELECTRON SOURCES
ELEMENTARY PARTICLES
ELEMENTS
ENERGY
FREE ELECTRON LASERS
FUNCTIONS
KINETIC ENERGY
LASERS
LEPTON BEAMS
LINEAR ACCELERATORS
MASSLESS PARTICLES
METALS
OPTICAL PROPERTIES
PARTICLE BEAMS
PARTICLE SOURCES
PHOTOCATHODES
PHOTONS
PHYSICAL PROPERTIES
QUANTUM EFFICIENCY
RADIATION SOURCES
TRANSITION ELEMENTS
WAVELENGTHS
WORK FUNCTIONS