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 μm) 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 2.5×10−3 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 104. 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 threshold emission field of 7.5 MV/m.