engleski

Status of the Low Emittance Gun Project Based on Field Emission

The design of an electron gun capable of producing beams with an emittance one order of magnitude lower than current technology would reduce considerably the cost and size of a free electron laser radiating at 0.1 nm. An electron source based on field emission is an attractive alternative for a high brightness source: thousands of high current density beams (10^8 A/cm^2) can be produced and individually focused. The development of a gun based on field emission cathodes implies many innovations in regards to current state of the art guns. The field emitter source will be inserted in a high-gradient diode configuration coupled with a radiofrequency (RF) structure. In the diode part a high electric field (several hundreds of MV/m) will limit the degradation of beam emittance due to space-charge effects. This first acceleration will be obtained with high voltage pulses (~500 kV in 500 ns) synchronized with the low voltage pulses applied between the tips and the extracting gate. This diode part will then be followed by an RF accelerating structure in order to bring the electrons to relativistic energies.

electron gun; free electron laser; field emission; high gradient acceleration

PSI = Paul Scherrer Institut, Villigen, Schweiz