Title :
Long pulse electron beams produced from carbon fiber cathodes
Author :
Fisher, Amnon ; Garate, Eusebio
Author_Institution :
Naval Res. Lab., Washington, DC, USA
fDate :
6/20/1905 12:00:00 AM
Abstract :
Carbon fiber cathodes have been used to produce electron beams from 10´s of nanoseconds to 10´s of microseconds. Cathode areas can vary from a single fiber (~10 micron diameter) to many hundreds of square cm. The micron size diameter of the fiber is responsible for the high electric field produced at the tips which allows operation of these cathodes at average fields as low as 10 kV/cm. During operation the emitting tips heat up and some plasma forms and erosion takes place. However, carbon has the highest sublimation energy per unit volume among all the elements. It does not melt and it sublimation temperature is high (4000 K). Therefore, no rounding of the tips take place (metals always melt and form a small sphere which turns off the emission). These properties allow producing cathodes with very million shot lifetimes at current densities of 10´s to 1000´s of A/cm2. We describe our work on carbon fiber cathodes which range in operation from 6 kV to 500 kV anode-cathode voltage and up to a few microseconds pulse duration
Keywords :
carbon fibres; cathodes; electron sources; C; carbon fiber cathodes; erosion; high electric field; long pulse electron beams; sublimation energy; sublimation temperature; Carbon dioxide; Cathodes; Current density; Electron beams; Laboratories; Mechanical factors; Particle beams; Physics; Plasma temperature; Solids;
Conference_Titel :
High-Power Particle Beams, 1998. BEAMS '98. Proceedings of the 12th International Conference on
Conference_Location :
Haifa
Print_ISBN :
0-7803-4287-9
DOI :
10.1109/BEAMS.1998.822402