Large-amplitude solitary waves in a relativistic nonisothermal plasma with warm ions

Large amplitude solitary waves in a relativistic plasma with non-isothermal electrons and finite ion temperature are studied using Sagdeev's pseudopotential technique. It is found that there exists a critical value of beta, the ratio of the temperatures of the free and trapped electrons respectively, beyond which soliton solutions cease to exist. This critical value depends on other parameters. Also the relativistic effect and finite ion temperature restrict the region of existence of solitary waves. A small amplitude expansion of the pseudopotential is derived to find different kinds of solitary waves.PACS Nos.: 52.35 Fp, 52.35 Sb, 52.35 Tc

Effects of the Shafranov shift on the ballooning mode in negative shear

In negative shear tokamak discharges, an excessively large Shafranov shift (Δ') destabilizes the magnetohydrodynamic ballooning mode. A kinetic model, local to a flux surface and which employs the ballooning-mode representation of the gyrokinetic equations, also predicts the existence of the instability as does two-fluid theory.PACS Nos.: 52.35.Fp, 52.35.Kt, 52.55.Fa