On the balance of stresses in the plasma sheet

摘要: The stress resulting from magnetic tension on the neutral sheet must, in a steady state, be balanced by any one or combination of (1) pressure gradient direction along axis tail, (2) similar plasma flow kinetic energy, and (3) anisotropy, with P∥ > P⊥ within sheet. Stress balance first two cases requires that ratios h/Lx Bz/Bx same order magnitude, where h is half-thickness sheet, Lx length scale for variations Bz Bx are field components just outside values usually quoted these quantities do not satisfy this requirement: too small and/or large. second case requires, addition, speed larger than Alfven third obey marginal firehose stability condition − = B²/μ0.