5:15 PM - 6:45 PM
[PEM17-P05] Study of higher-degree integrators for Vlasov simulation of double layers in the auroral acceleration region
Keywords:Vlasov simulations, electric double layers, advection equation
Electric fields in the acceleration region of the auroral zone have been studied via in-situ observations (e.g., Mozer et al. 1977; Ergun et al. 2001), which is known as electric double layers. The FAST observation showed detailed multi-dimensional structures of the auroral electric double layer (Ergun et al. 2001). Recently, observations by the Arase spacecraft have shown the presence of electric fields parallel to magnetic field lines in the magnetosphere at altitudes of 30,000 km (Imajo et al. 2020). Simulations of the electric fields in the auroral acceleration region have been performed by one-dimensional Vlasov equations (Newman et al. 2001). They have shown that electric double layers are generated by a strong density depression in a current-carrying plasma.
The present study aims to reveal the formation mechanism of double layers in a current-carrying plasma by Vlasov simulations. However, it is quite difficult to perform a hyper-dimensional Vlasov simulation even on a recent supercomputer due to the lack of both computing resources and accuracy of numerical schemes. We develop a higher-degree numerical integrator for the Vlasov equation, which could reduce the number of grid points in the velocity space.
Numerical integrators for solving the Vlasov equation in the previous studies have a numerical limiter which preserves non-oscillatory and positivity (Umeda et al. 2006,2012). However, these integrators have third- or fourth-degree accuracy, which are not enough for suppressing numerical diffusion. In the present study, we develop a fifth-degree integrator, which could preserve waveforms in the linear advection more than the previous integrators. The new integrator will be implemented into Vlasov code, and the comparison will be made against the formation of the electric double layer by Newman et al (2001).
The present study aims to reveal the formation mechanism of double layers in a current-carrying plasma by Vlasov simulations. However, it is quite difficult to perform a hyper-dimensional Vlasov simulation even on a recent supercomputer due to the lack of both computing resources and accuracy of numerical schemes. We develop a higher-degree numerical integrator for the Vlasov equation, which could reduce the number of grid points in the velocity space.
Numerical integrators for solving the Vlasov equation in the previous studies have a numerical limiter which preserves non-oscillatory and positivity (Umeda et al. 2006,2012). However, these integrators have third- or fourth-degree accuracy, which are not enough for suppressing numerical diffusion. In the present study, we develop a fifth-degree integrator, which could preserve waveforms in the linear advection more than the previous integrators. The new integrator will be implemented into Vlasov code, and the comparison will be made against the formation of the electric double layer by Newman et al (2001).