Screening Breakdown in a Plasma by Two Laser Fields and Strong DC Magnetic Field

Abstract

The effective static dielectric constant of an electron plasma system in the simultaneous presence of two electromagnetic waves and a strong DC magnetic field is calculated. It is found that as the difference ∆ω of the two electromagnetic wave frequencies matches the plasma frequency ωρ a breakdown in screening occurs thereby increasing the plasma heating rate via the external fields due to inverse Bremmstrahlung. An application is made by considering the typical parameters of a hot plasma.

Stopping of ions in a plasma irradiated by an intense laser field

“…The results have important applications in radiation and solid-state physics (Ritchie et al, 1975;Tung & Ritchie, 1977;Echenique, 1987), and more recently, in studies of energy deposition by ion beams in inertial confinement fusion (ICF) targets (Arista & Brandt, 1981;Mehlhorn, 1981;Maynard & Deutsch, 1982;Arista & Piriz, 1987;D'Avanzo et al, 1993;Couillaud et al, 1994). On the other hand, the achievement of high-intensity laser beams with frequencies ranging between the infrared and vacuum-ultraviolet region has given rise to the possibility of new studies of interaction processes, such as electronatom scattering in laser fields (Kroll & Watson, 1973;Weingartshofer et al, 1977Weingartshofer et al, , 1983, multiphoton ionization (Lompre et al, 1976;Baldwin & Boreham, 1981), inverse bremsstrahlung and plasma heating (Seely & Harris, 1973;Kim & Pac, 1979;Lima et al, 1979), screening breakdown (Miranda et al, 2005), and other processes of interest for applications in optics, solid-state, and fusion research. In addition, a promising ICF scheme has been recently proposed (Stöckl et al, 1996;Roth et al, 2001), in which the plasma target is irradiated simultaneously by intense laser and ion beams.…”

The Influence of Discharge Capillary Size, Distance, and Gas Composition on the Non-Equilibrium State of Microplasma

“…The rotational temperature of N 2 molecules calculated from the second positive system of N 2 (C 3 Π u →B 3 Π g ) was assumed to be equal to the translational temperatures and considered to be the gas temperature. This should be valid while considering the short times of rotational to translational energy transfer at atmospheric pressure . Indeed at atmospheric pressure, in He/N 2 plasma, N 2 (C‐B) emission yields a good measurement of gas temperature, and even for Ar/N 2 plasma, the gas temperature was determined accurately if the and levels of the N 2 (C) state chosen for gas temperature calculation …”

“…The other reason for selecting the N 2 second positive system for the measurements of rotational temperatures (and gas temperatures) in microplasmas was due to the fact that this band system could be observed in the discharge as long as there is an addition of the little amount of N 2 in the discharge gas. Moreover, the molecular constants describing this transition are well‐known, so that the calculation of the synthetic model spectra was made easily and with rather good accuracy . The wavelength of the corresponding transitions for N 2 second positive is expressed as given in Equation : where is the refractive index of air, and for and electronic states of N 2 taken from Ref .…”

“…For this reason, the gas temperature measurements in non‐equilibrium plasmas are often obtained by optical emission spectroscopy from the population distribution in rotational levels of excited states of nitrogen molecules (rotational temperature). This was adopted as well as utilized successfully by many researchers and was found to be accurate and reliable . On the other hand, in order for the discharge to be in non‐equilibrium, the energy gained in vibrational excitation should be greater than the energy lost by vibrational to translational ( V – T ) relaxation, and finally results in T vib > T trans ( T rot ), where the non‐equilibrium nature of the discharge is justified by the ratio of vibrational to rotational temperature ( T vib / T rot ) …”

Suppression of the plasma high-frequency electrical conductivity under a radiation field

“…Owing to the development of high-power radiation sources, there has been increasing interest in the study of the interaction of intense radiation fields with plasmas. Several phenomena were investigated amongst other, plasma heating via inverse bremsstrahlung regarding radiation fusion experiments [1][2][3][4][5][6][7][8][9][10][11] and plasma wave instabilities [12]. Another interesting aspect concerning the radiation-plasma interaction and the one which pertains to us here is the possibility of a radiation field control of the plasma dielectric properties.…”