Diffusion in a Strongly Coupled Magnetized Plasma

A first-principles study of diffusion in a strongly coupled one-component plasma in a magnetic field $B$ is presented. As in a weakly coupled plasma, the diffusion coefficient perpendicular to the field exhibits a Bohm-like $1/B$ behavior in the strong-field limit but its overall scaling is substantially different. The diffusion coefficient parallel to the field is strongly affected by the field as well and also approaches a $1/B$ scaling, in striking contrast to earlier predictions.

Figure 1

Diffusion coefficients (a) perpendicular and (b) parallel to the magnetic field as a function of the coupling parameter for the unmagnetized system and two moderate values of $B$. Also shown are the results of Daligault [14] (upper solid line), Bernu [20] (crosses), and from kinetic theory (BGL [19]).

Figure 2

Diffusion coefficients (a) perpendicular and (b) parallel to the magnetic field versus field strength $\beta ={\omega }_c/{\omega }_p$ for different $\Gamma$. The straight broken lines indicate a decay of ${\beta }^{-2}$, ${\beta }^{-1}$, and ${\beta }^{-0.3}$, respectively. Also shown are simulation data from Ref. 21 for $\Gamma =50$ (open diamonds) [22]. The open circles in (b) are predictions from BGL theory with a modified Rostoker kernel for $\Gamma =1$ and 10 [19].

Figure 3

$D_{\perp }$ in units of its field-free value (for the same $\Gamma$) for two field strengths, $\beta =0.5$ and 1.0.

Figure 4

$D_{\parallel }$ in units of its field-free value (for the same $\Gamma$) for $\beta =0.5$ and 1.0. Also shown are the integrated negative velocity autocorrelations (caging time; see text). Inset: the velocity autocorrelation function $Z(\overline{t})$ for three values of $\Gamma$.