Study of a laser-heated electron gun

Publisher Website
Google Scholar
Abstract
A method of cathode heating using a laser was studied for an electron gun. In order to observe the practicality of the heating system, the characteristics of the laser-heated gun with a dispenser and LaB6 thermionic cathodes have been experimentally investigated. The direct laser irradiation is so efficient that the gun is equipped without heat shielding, a cooling system, or an electrical circuit in the gun chamber for cathode heating. Modeling, based on the experimental data, indicates that the cathode temperature is proportional to one-fourth power of the laser power and that laser power loss and conduction loss of heat in the gun assembly are negligible. An electron beam current density 0.48 A/cm2 was measured with 26 W laser power for a dispenser cathode of 0.06 cm2 emission area. Current density 0.16 A/cm2 with 25 W was recorded for a LaB6 cathode of area 0.12 cm2. Electron beam emittance has been measured by using the typical pepper-pot technique. It was observed that the growth of electron beam emittance was very small in the laser heating.