Space-Charge Limitation of a Femtosecond Photoinjector

Abstract

Experimental investigation of a compact 40-kV diode-type photoelectric DC gun driven by 100 fs laser pulses revealed that the space-charge-limited current density could exceed 30 kA/cm 2 and that the density increased linearly with the accelerating voltage. We explained these important properties by the balance between the cathode surface field and the field produced by sheet-like electron bunches near the cathode surface. Our simple physical model agreed well with the experimental results.

Production of long bunch trains with4.5 μCtotal charge using a photoinjector

“…In addition, the saturation of the photoemission has been shown to be an effect related to the space charge effect during emission of charge per single pulse [10]. The total charge production with a long train of these pulses is shown to be independent of this saturation.…”

Modeling ultrashort laser-induced emission from a negatively biased metal

“…[11][12][13][14][15] The mechanisms of laser induced electron emission have been studied for a long time, 8,[16][17][18][19][20] but despite the widespread use of the phenomenon, there is no theory that adequately combines all the underlying processes. For instance, the electron distribution, charge transport, and carrier dynamics within the target, 12,[21][22][23] as well as surface effects [24][25][26][27] and the evolution of the charge density above the target, 23,[28][29][30][31][32] have been discussed intensively. All these processes influence each other, and have a considerable effect on the emitted charge.…”