Instability of Langmuir waves in plasma irradiated by directed gamma rays.

Abstract

In this Letter we investigate the possibility of Langmuir turbulence generation by directed gamma rays penetrating a background plasma. Turbulence is generated because Compton scattering creates superthermal electrons whose distribution can be unstable to the Cherenkov radiation of Langmuir waves. Using the Klein-Nishina cross section for relativistic Compton scattering, we calculate the momentum distribution of recoil electrons and derive the increment of instability for nonmagnetized plasma. The instability appears when there is a sufficiently narrow bump, for example, annihilation line $h\ensuremath{\nu}{\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}m}_{e}{c}^{2}$ with a width less than $0.3{m}_{e}{c}^{2}$, in the gamma spectrum.