Optimized loading for particle-in-cell gyrokinetic simulations

The problem of particle loading in particle-in-cell gyrokinetic simulations is addressed using a quadratic optimization algorithm. Optimized loading in configuration space dramatically reduces the short-wavelength modes in the electrostatic potential that are partly responsible for the nonconservation of total energy; further, the long-wavelength modes are resolved with good accuracy. As a result, the conservation of energy for the optimized loading is much better that the conservation of energy for the random loading. The method is valid for any geometry and can be coupled to optimization algorithms in velocity space. PACS Nos.: 52.35.Py, 52.30.Jb, 52.55.Fa

Effects of charge non-neutrality and finite beta on the electron temperature gradient modes in Tokamaks

Local kinetic analysis of the electron temperature gradient (ETG) mode in Tokamaks indicates that the effects of charge non-neutrality are significant in the parameter regime of Tokamaks. The maximum growth rate occurs at (k/kDe)2 [Formula: see text] 0.5 when the electron temperature and density are varied over a wide range. The growth rate becomes dependent on the β factor even though the ETG mode is predominantly electrostatic. Finite β stabilization of the ETG mode requires a large ballooning parameter so as to cause an effective drift reversal. Mixing length estimate yields an electron thermal diffusivity χe [Formula: see text] qνTe (c/ωpe)2 [Formula: see text] / Ln where c/ωpe is the electron skin depth. PACS Nos.: 52.65.Tt, 52.55.Fa, 52.35.Py

Relativistic kinetic theory of electromagnetic waves in equilibrium magnetized plasma. General dispersion equations

The relativistic kinetic theory of parallel propagating electromagnetic waves in a magnetized equilibrium plasma is presented. On the basis of relativistic Vlasov–Maxwell equations, a general explicit dispersion relation is derived by a correct analytical continuation for all complex frequencies of electromagnetic waves.PACS Nos.: 52.25.Dg, 52.25.Xz, 52.27.Ep, 52.27.Ny, 52.35.Hr, 52.35.Mw, 52.35.Py

Numerical loading of a Maxwellian probability distribution function

A renormalization procedure for the numerical loading of a Maxwellian probability distribution function (PDF) is formulated. The procedure, which involves the solution of three coupled nonlinear equations, yields a numerically loaded PDF with improved properties for higher velocity moments. This method is particularly useful for low-noise particle-in-cell simulations with electron dynamics. PACS Nos.: 52.35.Py, 52.30.Jb, 52.55.Fa