A current-carrying deuterium plasma ( ) has and

PHYSICS · Subjective · Fermi University Physics · Plasma Physics · Waves in plasmas · Kinetic theory, collisions and transport

Plasma Physics, Ch Hot plasmas and free energy: beam instabilities, cyclotron damping and Bernstein waves

Problem

A current-carrying deuterium plasma (

m_i = 2m_p

) has

T_e = 8.0\,\mathrm{eV}

and

T_e/T_i = 10

. For a hydrogen plasma at this same

T_e/T_i

the ion-Landau-damping contribution to the current-driven ion-acoustic threshold has been evaluated as the dimensionless "ion term"

= 0.0475

; because ion Landau damping depends on

T_i/T_e

and not on the ion mass, this value also applies here. The threshold drift for growth is

u \approx c_s\left[1 + \frac{\text{ion term}}{(m_e/m_i)^{1/2}}\right], \qquad c_s = \sqrt{T_e/m_i}.

Find the threshold electron drift

u

\mathrm{m\,s^{-1}}

, and express it as a multiple of

c_s