CERN Accelerating science

Article
Title	Field Emitter Arrays for a Free Electron Laser Application
Author(s)	Shing-Bruce-Li, Kevin ; Dehler, M ; Ganter, Romain ; Gobrecht, Jens ; Raguin, Jean Yves ; Rivkin, Leonid ; Wrulich, Albin F
Affiliation	(PSI, Villigen)
Publication	2004
In:	26th International Free Electron Laser Conference and 11th FEL User Workshop 2004, Trieste, Italy, 29 Aug - 3 Sep 2004, pp.e-proc. THPOS02
Subject category	Accelerators and Storage Rings
Abstract	The development of a new electron gun with the lowest possible emittance would help reducing the total length and cost of a free electron laser. Field emitter arrays (FEAs) are an attractive technology for electron sources of ultra high brightness. Indeed, several thousands of microscopic tips can be deposited on a 1 mm diameter area. Electrons are then extracted by applying voltage to a first grid layer close to the tip apexes, the so called gate layer, and focused by a second grid layer one micrometer above the tips. The typical aperture diameter of the gate and the focusing layer is in the range of one micrometer. One challenge for such cathodes is to produce peak currents in the ampere range since the usual applications of FEAs require less than milliampere. Encouraging peak current performances have been obtained by applying voltage pulses at low frequency between gate and tips. In this paper we report on different tip materials available on the market: diamond FEAs from Extreme Devices Inc., ZrC single tips from Applied Physics Technologies Inc. and Mo FEAs from SRI International.