Photofield emission from a tipped silicon photocathode in IR with a new picosecond Nd-YAG laser at a frequency of 100 MHz

Tipped silicon photocathodes are tested with the IR wavelength (1.064 mum) of a new lock-mode Nd-YAG laser. The impulse width of 30 ps is repeated at a frequency of 100 MHz at a power of 122 W. A quantum yield of 2.5 x 10(-3) is obtained in a DC gun using the best continuous emission field of 20 MV/ m for the photofield emission current. The ratio of the photofield emission current to the field emission current (dark current) is more than 10(4), A previous experiment with the second harmonic of a Nd-YAG at 10 Hz gave 700 pC per pulse of 35 ps width with a quantum yield of 10(-5) at the threshol d emission field of 7.5 MV/m. (C) 2000 Elsevier Science B.V. All rights res erved.