Absorption coefficient of electron cyclotron radiation in a plasma in the temperature range 5–20 keV

The coefficient of cyclotron absorption in a finite-density Maxwellian plasma is evaluated both analytically and numerically for temperatures and harmonic numbers requiring the finite electron gyro radius to be taken into account to terms of order higher than the lowest significant one commonly used. A comparison is made with results obtained to lowest signficant order and an exponential approximation is proposed which provides a good fit for a fairly wide range of temperatures and harmonic numbers. The emphasis of the numerical analysis is on the case of waves propagating perpendicularly to the magnetic field.