Abstract
This paper presents the results of experimental investigations into the current-voltage characteristics of a planar diode with an explosive emission cathode made from graphite. Studies were performed using a TEU-500 pulsed electron accelerator (350–500 keV, 100 ns, 250 J per pulse). Duration of diode operation, in a mode when electron current is limited by the emissive ability of the graphite cathode, is 15–20 ns. The contribution of the cathode periphery to total electron current appears only as an increase in the emissive surface area due to an expansion of explosive plasma. Investigations of an ion diode with a graphite cathode (plane and focusing geometry) were also carried out. Experiments were performed using a TEMP-4M ion accelerator, which forms two nanosecond pulses: the first negative pulse (150–200 kV, 300–600 ns) followed by the second positive (250–300 kV, 150 ns). Total diode current in the first pulse is well described by the Child-Langmuir law for electron current at a constant rate of plasma expansion, equal to 1.3 cm/μs. It is shown that for an area of flat cathode over 25 cm2, the influence of edge contribution does not exceed measurement error of total diode electron current (10%).
Highlights
Investigations into the behaviour of diodes with an explosive emission cathode during the generation of a pulsed electron beam of current density exceeding 20 A/cm2 have been carried out since the 1970s
From the Advances in High Energy Physics moment voltage is applied until a dense plasma forms on the cathode surface, the electron current is limited by the emissive ability of the cathode
In our previous study 16, we reported on the operation of a planar diode with a graphite explosive emission cathode
Summary
Investigations into the behaviour of diodes with an explosive emission cathode during the generation of a pulsed electron beam of current density exceeding 20 A/cm have been carried out since the 1970s. It has been shown that the electron current is limited either by the emission ability of the cathode or by the space charge in the anode-cathode gap A-K gap 1, 2. From the Advances in High Energy Physics moment voltage is applied until a dense plasma forms on the cathode surface, the electron current is limited by the emissive ability of the cathode. It is obvious that the mode of current limitation by space charge is preferable from the standpoint of diode stability. In this mode, the current does not depend on the emissive ability of the cathode but is rather determined only by the geometry of the diode and accelerating voltage. Current distribution over the beam cross-section is more homogeneous
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
