Short-pulse high-current-density photoemission in high electric fields
We present the experimental results of photoemission studies on thin wires of gold-coated tungsten, held at surface fields in the range of 10/sup 6/ to 3 x 10/sup 8/ V/m, and illuminated by 10 ps long, 4.66 eV photon laser pulses. The wire cathodes arranged coaxially in an anode experienced a surface-field enhancement of 10/sup 2/ to 10/sup 3/ over the applied voltage. We obtained current densities exceeding 10 kA/cm/sup 2/ from a 50 ..mu..m diameter wire, from a (50 x 400) ..mu..m/sup 2/ area, under partially space-change-limited conditions. The quantum efficiency for emission-limited cases was in the range of 10/sup -5/. For these cases results using 50 ..mu..m and 4 ..mu..m diameter wires indicated linear dependence of charge density with optical energy density. The emission also scaled linearly with the emitting area. For surface fields above 3 x 10/sup 7/ V/m, a twofold enhancement of emission was observed for a tenfold increase in the field. 7 refs., 9 figs.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 6380939
- Report Number(s):
- BNL-40224; CONF-8706147-7; ON: DE87014909
- Country of Publication:
- United States
- Language:
- English
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75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACCELERATORS
CATHODES
CURRENT DENSITY
DATA
EFFICIENCY
ELECTRIC FIELDS
ELECTRODES
ELECTRON SOURCES
ELEMENTS
EMISSION
EXPERIMENTAL DATA
GOLD
INFORMATION
LASERS
METALS
NUMERICAL DATA
PARTICLE SOURCES
PHOTOCATHODES
PHOTOEMISSION
PULSES
QUANTUM EFFICIENCY
RADIATION SOURCES
SECONDARY EMISSION
TRANSITION ELEMENTS
TUNGSTEN