Electrical conductivity of plasmas of DB white dwarf atmospheres

Abstract

The static electrical conductivity of non-ideal, dense, partially ionized helium plasma was calculated over a wide range of plasma parameters: temperatures $1\cdot 10^{4}\textrm{K} \lesssim T \lesssim 1\cdot 10^{5}\textrm{K}$ and mass density $1 \times 10^{-6} \textrm{g}/\textrm{cm}^{3} \lesssim \rho \lesssim 2 \textrm{g}/\textrm{cm}^{3}$. Calculations of electrical conductivity of plasma for the considered range of plasma parameters are of interest for DB white dwarf atmospheres with effective temperatures $1\cdot 10^{4}\textrm{K} \lesssim T_{eff} \lesssim 3\cdot 10^{4}\textrm{K}$. Electrical conductivity of plasma was calculated by using the modified random phase approximation and semiclassical method, adapted for the case of dense, partially ionized plasma. The results were compared with the unique existing experimental data, including the results related to the region of dense plasmas. In spite of low accuracy of the experimental data, the existing agreement with them indicates that results obtained in this paper are correct

Astrophysical and laboratory plasmas: HF properties under extreme conditions

“…We here continue our previous investigations of plasma static electrical conductivity which are of interest for DB white dwarf atmospheres (see e.g. [12,13]).…”

“…τ (E) being the 'static' relaxation time. The method of determination of τ (E) is described in the previous papers [6][7][8][9][10][11] in detail.…”

Modeling of continuous absorption of electromagnetic radiation in dense partially ionized plasmas

“…Just this kind of situation is realized in a plasma of the kind treated in this paper, i.e. with N e of the order of magnitude of 10 −19 cm −3 and T of about 20 000K, where the ion Wigner-Seitz radius r s;i is close to the ion screening radius r e given by (9), making an application of DH potential completely unacceptable. Let us emphasize the fact that the same is valid for any other potential which has a similar meaning as DH.…”

Survivability of radio-loud planetary cores orbiting white dwarfs

“…Generally these conductivities decrease with increasing white dwarf cooling age; Fig. 4 of Mazevet et al (2007) indicates that this trend continues for (older) white dwarfs with effective temperatures under 8000 K. As previously mentioned, we do not know how the conductivities of DA (hydrogen-dominated) white dwarf atmospheres compare with the results of Srećković et al (2010). All these considerations led us to adopt the range γ * = 10 −1 -10 4 S/m.…”

“…Therefore, we use a sufficiently wide range of conductivities to encompass plausible values. Table 2 of Srećković et al (2010) provides static electric conductivity values of DB (helium line-dominated) white dwarf atmospheres for a range of equilibrium temperatures between 8000 K -75,000 K and plasma mass densities between 5 × 10 −7 g/cm and 5 × 10 −3 g/cm. The conductivities for all these values range over six orders of magnitude, from γ * = 6.88 × 10 −2 -9.84 × 10 4 Siemens/metre (or, equivalently, Mho/metre or 1/Ohm×metre).…”