Developing a Linear Fluid Plasma Model with Accurate Kinetic Bernstein Waves: A First Step

Kinetic models provide highly accurate descriptions of plasma waves but involve complex integrals that are computationally expensive to solve. To facilitate a fluid-like treatment of the system, we propose rational approximations for both the plasma dispersion function in the parallel integral and the Bessel function in the perpendicular integral, ensuring that the system remains rational with respect to all three variables: wave frequency $ω$, parallel wavevector $k_\parallel$, and perpendicular wavevector $k_\perp$. By accurately approximating the Bessel function over a wide range of Larmor radius $ρ_{cs}$ values, from $k_\perpρ_{cs} \to 0$ to $k_\perpρ_{cs} \to \infty$, we present an initial attempt to incorporate kinetic Bernstein waves into a fluid model. As an application, we employ this model to analyze { electromagnetic plasma} wave propagation conditions (i.e., accessibility) by solving for the complex perpendicular wavevector $k_\perp$ using a matrix eigenvalue method with given input parameters. This work may contribute to studies of electron cyclotron resonance heating (ECRH) and ion cyclotron resonance frequency (ICRF) heating in magnetized confinement plasmas.