A tokamak of major radius is heated by fundamental electron cyclotron resonance at…

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 tokamak of major radius R0=3.0 mR_0 = 3.0\,\mathrm{m} is heated by fundamental electron cyclotron resonance at the magnetic axis (x=0x=0, so R0+x=R0R_0+x=R_0), with k∥/k=0.20k_\parallel/k = 0.20 and electron thermal speed vte=0.10cv_{te} = 0.10c. Using the Doppler-width formula Δx/(R0+x)≈(k∥/k)(vte/c)\Delta x/(R_0+x) \approx (k_\parallel/k)(v_{te}/c), find the width Δx\Delta x of the cyclotron damping layer.

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