Effects of collisions on the trapped particle mode in a linear machine

The effects of weak Coulomb and neutral collisions on the collisionless curvature driven trapped particle mode are studied in the Columbia Linear Machine [Phys. Rev. Lett. 57, 1729(1986)] by means of particle-conserving Krook and Fokker--Planck operators. Both types of collisionality are then combined, modeling neutral collisions with the conserving Krook and Coulomb collisions with a Lorentz model. The dispersion relation is then integrated over velocity space. Low Coulomb collisionality yields a small stabilizing correction to the magnetohydrodynamic collisionless mode, which scales as ν/sub e/ using the Krook model and ν/sup 1/2//sub e//sub C/ using a Lorentz pitch-angle operator. In higher collisionality regimes, both models tend to yield similar scalings