A helium plasma (singly ionised

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

Plasma Physics, Ch The Vlasov equation and Landau damping

Problem

A helium plasma (singly ionised, ion mass mi≈4mpm_i \approx 4m_p with mp/me=1836.15m_p/m_e = 1836.15) has Te/Ti=12T_e/T_i = 12. Using the ion-acoustic weak-damping formula γω≈−π8[(memi)1/2+(TeTi)3/2exp⁡(−Te2Ti−32)],\frac{\gamma}{\omega} \approx -\sqrt{\frac{\pi}{8}}\left[\left(\frac{m_e}{m_i}\right)^{1/2} + \left(\frac{T_e}{T_i}\right)^{3/2}\exp\left(-\frac{T_e}{2T_i}-\frac{3}{2}\right)\right], find γ/ω\gamma/\omega and state which term dominates.

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