Hu Xi-Wei

The Stimulated Brillouin Scattering of a Strong Laser in Partially Stripped Plasmas

The effects of the nonlinear polarization in a partially stripped plasma on stimulated Brillouin scattering (SBS) process of a strong laser are discussed. A set of nonlinear mode coupling equations and the linear growth rate of SBS instability is derived, respectively. When the intensity of an incident laser I0 > 1017 W/cm2, the third order susceptibility χ(3) will reduce the above mentioned linear growth rate enormously. If taking the maximum value of the second order susceptibility χ(2), the growth rate may be decreased observably when I0 > 1014 W/cm2. Furthermore, the nonlinear susceptibility can affect the nonlinear evolution of SBS much extensively.

Simulation of nonlinear behavior in an electron cyclotron resonance plasma

Some nonlinear behavior in electron cyclotron resonance plasma was investigated using a two-dimension hybrid-mode with self-consistent microwave absorption. The saturation, oscillations of plasma parameters (plasma density, potential, electron temperature) versus operating conditions (pressure, power) are discussed. Our simulation results are consistent qualitatively with many experimental measurements.

Parameter Processes of a Strong Laser in Partially Stripped Plasmas

The effects of the nonlinear polarization in a partially stripped plasma on the parameter processes of a strong laser are discussed. The nonlinear mode coupling equations of stimulated Raman scattering (SRS) are derived. The linear instability growth rates of SRS and stimulated Brillouin scattering (SBS) are given. When the pump wave intensity Io > 1017 W/cm2, the third order susceptibility associated with bound electrons will reduce the SRS and SBS linear growth rate enormously. In addition, the nonlinear susceptibility can affect the nonlinear evolution of SRS and SBS significantly.

Nonlinear Description of Stimulated Raman Scattering and the Corresponding Four-Wave Process

Nonlinear behaviors of the stimulated Raman scattering and the corresponding four-wave process (ω0 → ωs + ωp1 + ωp2) are discussed. The analytic and numerical solutions of the coupling equations which count the decay of the pump wave have been given. The difference between three-wave and four-wave parameter processes is also indicated.

Three Wave Mixing and Four Wave Scattering Processes in Laser-Plasma Interaction

A nonlinear fluid description for the parameter processes has been derived. The linear instability analyses about three wave mixing process ω0 → ωs1 + ωs2 and four wave scattering process ω0 → ωs + ωp1 + ωp2 have been made. Correspondent backward or side scattering light waves emitted from mentioned processes may provide valuable information for the diagnostic of plasma parameters.

Mechanism of Low Pressure dc Breakdown in a Thermo-Cathode Gas Discharge

A theory about the dc breakdown process of a gas discharge with thermo-cathode in a very low pressure (10-2 Pa) is provided. The mobility of ions due to ion-neutral charge exchange collisions is mainly responsible for the space cumulative effect of positive charges and the formation of the virtual anode. A numerical result for the breakdown process of the argon gas discharge is given.

Axial Shock in a Cylindrical Plasma with Current

Hugoniot relations of a two-dimensional axial shock with current and magnetic field in a cylindrical shock tube were investigated by a numerical method. The radial profiles of the magnetic field, electric current, pressures, flow velocities and temperatures between the up- and down-stream radial force-balanced plasma of the shock were revealed by numerical analysis. It is clearly found that the axial shock can lead to two effects: one is an inverse skin effect (i.e., the current density rises towards the center of the conductor), the another is a reversed current effect which occurs near the edge and about a half radius. It is also found that the radial gradient of pressure, density and temperature all become very large near the center due to the axial shock.

Ions confinement in electron beam ion trap

This paper shows the evolution of density and temperature of multi-charged ions in an electron beam ion trap (EBIT). Three cases are studied: the continuous neutral gas injection, ion source injection, and evaporative cooling. The effects of the neutral gas density, axial potential, and the beam current density on the ions evolution are discussed.

Triple Plasmon Decay of Electromagnetic Pump Wave

A fluid description of the triple plasmon decay process has been provided. The linear and nonlinear analyses suggest that this parameter process will occur very likely at the local area where the plasma density is about nc/9. The analyses with saddle point method of integration indicate also that the triple plasmon decay process is absolutely unstable.

A New Turbulent Collision Integral in Plasma Kinetic Equation

A new turbulent collision integral is derived from the first and second BBGKY equations, in which the effects of well-developed turbulent field are taken into account. The turbulent collision integral contains turbulent frequency-wave number spectrum and up to fourth order differential of particle distribution function.