Lower hybrid (LH) wave instability excited due to an electron beam in a spin-polarized degenerate plasma is studied. Using the Separate Spin Evolution quantum hydrodynamic model, incorporating Coulomb exchange interaction and Bohm potential, the general dispersion relation of nearly perpendicular propagating electrostatic waves is derived. Furthermore, in the low-frequency limit, the dispersion of LH wave is obtained. It is found that the electron spin polarization and beam streaming speed reduce the growth rate as well as the k-domain. However, the beam density and the propagation angle enhance both the growth rate and k-domain of LH instability. In addition, the contribution of the Bohm potential term increases the intensity of the growth rate. All these effects may have a strong bearing on the wave and instability phenomena in spin-polarized plasmas. KEYWORDS electron beam, exchange interaction, solid state plasma, spin polarization
INTRODUCTIONThe quantum effects play quite an important role in the study of astrophysical environments like white and brown dwarfs, neutron stars, magnetars, and core of giant planets (e.g., Jovian planets) [1][2][3][4] and in the laboratory environment, for example, laser-produced plasma, [5] in the development of nanostructured materials, [6] quantum wells, [7] and in the study of ultra-cold plasmas. [8] In order to understand such problems, a quantum version of the classical hydrodynamic model, later named quantum hydrodynamic (QHD) model, has been developed and extensively used to study the properties of plasma waves, streaming, and wake effects in the plasma. [9][10][11][12][13][14][15][16] Recently, the QHD model has been derived in the frame work of local density approximation. This modified QHD model contains the finite temperature effect, correction in Bohm potential, and exchange correlation potential effects. Furthermore, the applicability of QHD model for different range of wave numbers and frequency has been discussed. [17] Using the QHD model and incorporating the electron exchange-correlation effects, the parametric instabilities induced by the non-linear interaction between high-frequency quantum Langmuir waves and low-frequency quantum ion-acoustic waves have been studied in Ref. [18]. The electron spin effect is another quantum effect that has been extensively studied in the plasma waves and instabilities during the last decade. To understand the electron spin effects on the wave dispersion characteristics in quantum plasma, the QHD model for spin-1/2 particles was presented by Kuz'menkov. [19,20] Moreover, to understand the non-linear dynamics of spin-1/2 quantum plasmas, the QHD model for spin-1/2 particles has been derived and its usefulness demonstrated in solid-state plasma as well as in astrophysical plasma. [21] The QHD model for spin-1/2 particles has received a great deal of attention due to emergence of some new wave phenomena and its effect on instabilities. [22][23][24][25][26][27][28][29] Subsequently, the kinetic quantum model for spin-1/2 quantum p...