Boris K. Frolov

Simulation of plasma afterglow phase in an inertial fusion energy chamber

A zero-dimensional model that describes the evolution of plasma and gas parameters during the afterglow phase of cyclic operation of an inertial fusion energy chamber is developed. The afterglow phase determines the conditions for next fuel-target injection and therefore its thorough analysis is very important for conceptual design of inertial fusion power plants. The model incorporates important effects of intrinsic impurity ion radiation on plasma cooling as well as of chamber opacity with respect to resonance radiation on plasma recombination in the working chamber. The decay times for the plasma and gas energy and, in particular, their dependence on initially stored energy, chamber size, and background gas concentration are analyzed. The heat power load onto the cryogenic fuel target due to residual plasma, gas, and radiation field is calculated. It is found that the higher the background gas density, the longer is the time into the afterglow phase necessary to reduce the heat flux on the target to an...

On intense electron beam propagation through gas jets

The structure of the ionization front created by an expanding high-intensity electron beam as it travels through ∼1atm gas is considered theoretically. The velocity of the front, Vf, on the order of a few 10∧9cm∕s, is determined by the electric field ionization process. When decreasing the gas density, the velocity Vf decreases relatively slowly up to some threshold, after which it starts rapidly falling. The magnitude of Vf is higher for argon than for helium. These findings are supported by experimental observations.

Impact of field ionization on the velocity of an ionization front induced by an electron beam propagating in a solid insulator

The propagation of an intense electron beam through a solid density insulator is analysed. The asymptotic behaviour of the front velocity is found for large beam densities. We show that at high beam densities the front velocity starts to fall when the induced E-field becomes strong enough to neutralize itself (through field ionization followed by self-consistent charge neutralization). We also show that the effect of the polarization current (caused by the E-field removing electrons from atoms) on the magnitude of the ionization front velocity, although noticeable, does not change the qualitative picture derived when neglecting it.

Propagation of a dense relativistic electron beam through a gas

The ionization front induced by a relativistic high-density electron beam in a gas was studied in a one-dimensional (1D) approximation. The expression for the beam density corresponding to a steady front propagation was found in the limit of large (∼c) and small (⪡c) front velocities. The corresponding expression for front velocity was also found and the validity of the approximations used was verified. Finally, the values of front velocity and beam density were calculated for a wide range of beam energies and gas densities. The calculated values of the front velocity are in good agreement with the experimental data [D. Batani, S. D. Baton, M. Manclossi et al., Phys. Rev. Lett. 94, 055004 (2005).].