Breakdown of a coaxial diode transverse to the magnetic field

Abstract

It is noted that the modern development of pulsed power generators with fast energy storage systems in the range of several megajoules makes it necessary to find conditions for charge particle beam formation with the same energy characteristics. Presently, the highest parameters of electron beams (E/sub 0/=140 kJ) are obtained in coaxial diodes, with magnetic insulation. However, even in these experiments the energy transport efficiency from a storage system into the beam was only approximately 20%. One of the main reasons for low efficiency is the breakdown in the diode transverse to the magnetic field. A breakdown centrifugal instability model is described and compared with experiments. It is shown that, in order to raise the electron-beam energy in coaxial diodes it is necessary to suppress the centrifugal instability in the plasma created on the inner diode electrode. For inner cathode diodes it is advisable to use a nonuniform magnetic field configuration with the field strength increasing rapidly enough in the direction from cathode to anode. The large radius diode with uniform magnetic field also seems to be promising for this purpose. >