Investigation of the particle spin properties on the velocity space instability in high‐density plasmas

Abstract

The nonresonant electromagnetic instabilities of the anisotropic velocity space (Weibel-like) have always been one of the interesting subjects for researchers. These electromagnetic instabilities play an important role in generating strong magnetic fields in laboratory plasmas for applications such as inertial confinement fusion and space plasmas. In this paper, we investigate the quantum effects of the particle spin on the electromagnetic instabilities. In the case of the presence of a magnetic dipole force and an electron precession frequency like the Vlasov equation, we derive the full quantum equation. This study shows that, in the presence of the spin-polarized effects, the growth rate of the instabilities is reduced compared to the classical cases and will not arise for low fractions of the temperature anisotropy for different values of the magnetic field. Indeed, it is expected that the probability of electron capture in the background magnetic fields and the effective collision with the particle increase because of the spin effect, so that a high portion of the electron energy is transmitted to the background plasma, and the temperature anisotropy governing the electron distribution is reduced. KEYWORDS electron precession frequency, magnetic dipole force, nonresonant instability, temperature anisotropy INTRODUCTIONQuantum plasma physics has many applications, for example, in the fields of high-intensity laser-plasma interaction, [1,2] metal and semiconductor nanostructures, [3,4] and astrophysical plasmas. [5,6] The electron density in semiconductors is much smaller than that in metals but the de Broglie wavelength of the charge carriers is comparable to the spatial scale of the profile. Therefore, the quantum effects associated with quantum tunneling particle dispersive effects (delocalized wave functions) can become important. As is known, the spin motions of quantum systems and the magnetization related to the intrinsic spin can be important in semiconductors, in metal alloys, and, more generally, in magnetic nanostructures. [7][8][9][10] For example, it is known that magnetic moment motion allows the magnetoresistive read-heads to respond to the bits of hard disks for memory. In the field of laser plasmas, in particular inertial confinement fusion (ICF) plasmas, the spin-polarized fuel idea was proposed initially by More. [11] Investigations have shown that the thermonuclear cross-section can increase by 50% by using spin-polarized D-T fuel. Consequently, the ignition thresholds can be reduced and the fraction of the fuel burned can be increased before target disassembly. Also, the driver energy required can be reduced by the spin-polarized fuel. In addition, the use of spin-polarized fuel can lead to an anisotropic emission of -particles in the fusion reaction product. This anisotropy spatially concentrates the plasma self-heating and leads to the development of fuel ignition. [12][13][14] In ICF, a large portion of the driver energy must be converted to fusion energy of the nuclear fuel for reachin...