The linearized Vlasov–Poisson equations, which combine to an integrodifferential equation for the perturbed electric potential, are used to investigate the effect of finite plasma size on the stability of electrostatic waves in a homogeneous plasma slab. The distortion of the gyromotion of the particles at the plasma boundary influences wave stability, a phenomenon termed the boundary Larmor radius (BLR) effect. The integrodifferential equation, treated as an eigenvalue problem, is discretized into a matrix dispersion equation by use of the Galerkin method and is then solved numerically. It is found that the ion Bernstein wave, which is undamped in an infinite homogeneous plasma, now becomes damped with a maximum damping rate of 0.35 ωci at rG/L (ion Larmor radius over wall distance)≊0.15. In general, the damping is less pronounced at shorter perpendicular wavelengths. It implies a necessity to take into account the BLR effect in the kinetic stability studies for sufficiently large ion Larmor radius in comparison to the characteristic dimension.

1.
By “finite” we here mean “not infinite in all dimensions.” The plasma need not be spatially bounded. The same applies when we say “bounded plasma.”
2.
R. C.
Davidson
,
Phys. Fluids
19
,
1189
(
1976
).
3.
We have also performed a similar calculation for the periodical boundary condition φ(x+L) = φ(x). It gives qualitatively the same results as the zero boundary condition.
4.
B. D. Fried and S. D. Conte, The Plasma Dispersion Function (Academic, New York, 1961).
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