Hysteresis in Stability Conditions of Electron-Hole Plasma

Abstract

The investigation of the hysteresis occurring in the threshold conditions for the helical instability oscillations in electron-hole plasma has been extended. The hysteresis in electric field strength $E$ can exceed 45 V/cm and 50% of the applied $E$ at threshold. By determining the stability-instability boundary in the $p$-type InSb as a function of the parallel (or antiparallel) electric and magnetic field strengths and also the plasma density, the magnetic field induced by the formation of the helical density perturbation is deduced. Resulting displaced loop $B\ensuremath{-}H$ curves are presented. The magnitude of the induction enhancement ${B}_{\mathrm{hys}}$ can be as large as 165 Oe and 55% of the applied $B$ at threshold. The extent of applied magnetic field (or electric field strength) over which the loops can occur is limited at the high magnetic field end (typically \ensuremath{\le}600 G) by vanishingly small plasma density and at the other end (\ensuremath{\ge}280 G) by the occurrence of magnetic pinching. The loops are largest at the low magnetic field end. The range of loop energy, defined as the product of ${E}_{\mathrm{hys}}$ and ${B}_{\mathrm{hys}}$, increases with decreasing plasma cross-sectional area until saturation occurs at a plasma radius of \ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}2}$ cm. The full range from largest to smallest loop in any one sample is achieved by a relatively small variation in the input energies, i.e., the product of the magnetic and electric field strengths at threshold.