Influence of an Upper-Hybrid Pump on Temperature Relaxation Process

V. N. Pavlenko and V. G. Panchenko
Institute for Nuclear Research of the National Academy of Sciences of Ukraine,
Prospekt Nauki, 47, Kyiv, 03680, Ukraine
Abstract. By means of kynetic fluctuation theory, the relaxation process between the electron and ion temperatures in a
magnetized homogeneous plasma is considered. The cases when external upper-hybrid pump wave excites convective
and ion-acoustic waves are analyzed. The inverse relaxation time in the regime where the turbulent fluctuations are
developed is calculated and its dependence on the pump wave and plasma parameters is deduced.
Keywords: relaxation, upper-hybrid pump, magnetized plasma.
PACS: 52.35-g
The theory of temperature relaxation was developed in Refs. [1 – 3] for an isotropic and magnetized plasma and
also for a plasma subjected to external electromagnetic radiation. It has been found in [4] that a high-frequency
electrostatic field close to the lower-hybrid resonant frequency has a significant influence on the relaxation rate
between the electron and ion temperatures in magnetized uniform plasma.
Consider electron-ion plasma in an external magnetic field Boz
r
Furthermore, the plasma is subjected to an HF pump field, wher e electric field is directed perpendicular to the
external magnetic field. For a long-wavelength (k0 = 0) pump wave we can write E(t) = E0 y cosω0t
ur ur
.
First, we consider the case when the pump wave frequency is close to the upper-hybrid frequency:
Here ωc = (mi /me )1/ 2 ⋅Oi ⋅cosΘ is the frequency of the modified convective cell, and γ c is the decrement
of the wave damping,
1
c 2 ei γ ≈ ν , where ν ei is the electron-ion collision frequency, Θ is the angle between k
r
and B0
uur
. It should be noted that convective modes arise in magnetized plasma with a small ratio of the plasma
pressure to the magnetic pressure, and can also occur in the ionospheric plasma [5].
The dipole approximation is assumed for the pump wave, because typical ionospheric plasma parameters
satisfy the condition k0 / k0⊥

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