HIGH PULSED CURRENTS FROM PHOTO-FIELD EMITTERS

Différent microemitters - single or arrays - with various geometries and kinds of material have been irradiated with pulsed laser beams. These emitters working in photo-field emission regime delivered very high intensity electron bunches. Peak intensities as high as some tens of Amps with less than one ns duration have been obtained with U.V. light. New type of microemitters developed in collaboration with BNL have been tested since last year showing the possibility of obtaining charges above 20 nC with low energy laser puises, (εi = 100µJ). The main parameters affecting the choice of these emitters as quantum yield, photocurrent density, electron pulse length, repetition rate and vacuum system level are here discussed. Good performances obtained with these emitters as well as the absence of cesiation make these microemitters interesting candidates for the new generation of linac injectors as well as for multimegawatt RF sources. At LAL, Orsay efforts have been made since three years to develop such electron sources

Canon à électrons à forte brillance utilisant une cathode en borure de lanthane

An electron source using a LaB6 cathode is investigated. Results and methods of measuring current beam intensity and brightness of LaB 6 are given in this paper. Comparison is made between our results and results obtained by others authors using W cathodes.Un canon à électrons associé à une lentille électrostatique à 3 électrodes, capable de fournir un courant de quelques mA et un spot de 1 mm de diamètre à 1 m de la cathode a été étudié Le canon utilise une cathode en borure de lanthane. La méthode de mesure de la brillance du faisceau est décrite. A tension d'accélération égale, la brillance obtenue est au minimum 100 fois supérieure à celle des canons à cathode de tungstène