Study on high-voltage, high-brightness pseudospark electron beam characteristics and emission mechanism

A high-energy (200 keV) high-brightness (8×10¹⁰ A/cm²) pseudospark electron beam was generated. Its beam quality was much better than that of cold-cathode beams. A solid and layer-like beam structure was observed. The propagation range of ⩾25 cm was useful for compact gas-loaded FELs. Field-induced explosive electron emission is considered to be more likely the most possible mechanism for pseudosparks by solving 1-D heat conduction equation with Joule-heating source for a micropoint on a cathode surface. The mean electric field on the cathode surface up to 1-5 MV/cm prior to the conducting phase is enough to initiate the mechanism at high threshold current density (⩾10⁸ A/cm²) and within very short time (<10 ns)