High power cross-modulation plasma diagnostics

Cross-modulation in helium was extended far beyond the power limit for small signal perturbation permitted by standard methods. By measuring e-folding times for the non-exponential relaxations together with modulation depths the electron collision frequency was found. The results yielded close agreement with calculations based upon published collision cross-sections when heating wave self-modulation was taken into account. This was done by a numerical procedure. (Auth.)