The results of an experimental investigation of the plasma dynamics in a magnetically insu- lated ion diode in bipolar-pulse mode are presented. The experiments were done at the pulsed TEMP-4M accelerator by formation...The results of an experimental investigation of the plasma dynamics in a magnetically insu- lated ion diode in bipolar-pulse mode are presented. The experiments were done at the pulsed TEMP-4M accelerator by formation of a first negative pulse (100 ns, 150-200 kV) and a second positive pulse (80 ns, 250-300 kV). The voltage-current diode characteristics were used to analyze the plasma behavior in the anode- cathode gap. It is shown that, during the first pulse, a discrete emissive surface is formed on the graphite potential electrode and a plasma forms by explosive-emission, which before the second pulse comes, fills the whole working surface of the electrode and spreads to the anode-cathode gap. An analytical expression is obtained for the total current in the cellular structure approximation. It is shown that the current build-up for a cathode surface with dis- crete emitting centers is described satisfac- torily by a modified Child-Langmuir formula wi- th a form factor decreasing from F = 6 to 1. It is found that, once plasma formation at the gra- phite potential electrode is complete and until the second positive pulse, the plasma speed is constant and equals 1.3 ±0.2 cm/μs.展开更多
文摘The results of an experimental investigation of the plasma dynamics in a magnetically insu- lated ion diode in bipolar-pulse mode are presented. The experiments were done at the pulsed TEMP-4M accelerator by formation of a first negative pulse (100 ns, 150-200 kV) and a second positive pulse (80 ns, 250-300 kV). The voltage-current diode characteristics were used to analyze the plasma behavior in the anode- cathode gap. It is shown that, during the first pulse, a discrete emissive surface is formed on the graphite potential electrode and a plasma forms by explosive-emission, which before the second pulse comes, fills the whole working surface of the electrode and spreads to the anode-cathode gap. An analytical expression is obtained for the total current in the cellular structure approximation. It is shown that the current build-up for a cathode surface with dis- crete emitting centers is described satisfac- torily by a modified Child-Langmuir formula wi- th a form factor decreasing from F = 6 to 1. It is found that, once plasma formation at the gra- phite potential electrode is complete and until the second positive pulse, the plasma speed is constant and equals 1.3 ±0.2 cm/μs.
