Formation of New Emission Centers on the Cathode

Research on an improved explosive emission cathode

“…It has been confirmed that the emission mechanism of an EEC lies in the explosions of the micropoints on the cathode surface and the subsequent formation of a cathode plasma [6][7][8][9]. This plasma also places a fundamental limit on both the maximum pulse duration (because of accelerating gap closure) and the repetition rate (because of gas evolution).…”

“…The main mechanism for generating the cathode plasma in EEE was stated as the explosions of metallic microprotrusions on the cathode surface which were caused by heating of the field-induced thermal-assisted pre-currents [6][7][8][9]. However, the experiments on cathode plasmas revealed that the dominant positive components in a cathode plasma were hydrogen ions [10].…”

“…We think that the difference between experiments in the literature [6][7][8][9] and the ones in [10][11][12] stems from the different experimental conditions. The microprotrusion model in [6][7][8][9] could describe the EECs that are carefully cleaned and operated in high, oil-free vacuum conditions, hence the simulations based on the model in [13] are in good consistence with the experimental results.…”

“…We think that the difference between experiments in the literature [6][7][8][9] and the ones in [10][11][12] stems from the different experimental conditions. The microprotrusion model in [6][7][8][9] could describe the EECs that are carefully cleaned and operated in high, oil-free vacuum conditions, hence the simulations based on the model in [13] are in good consistence with the experimental results. In most practical applications of EECs, the working chambers are only pumped down to about 10 −3 -10 −2 Pa, and the electrode surfaces are covered by layers of adsorbed gases (such as H 2 , H 2 O, CO, CO 2 and hydrocarbons) and dielectrics (such as non-metallic inclusions and oxide layers) of different thicknesses between 1 and 100 nm depending on the electrode preparation and the vacuum condition of the working chambers [10,14].…”

“…When a high-voltage pulse is applied to the gap of the diode, field-induced pre-currents originate from the micropoints with larger field-enhancement factors and smaller work functions on the cathode surface. The pre-currents could be as high as 10 8 A cm −2 [7,8,18,19]. Limited by the space charge effect, the pre-currents, even with the thermal assistance, would not directly lead to the explosions of the micropoints in several nanoseconds [19].…”