A dynamical model is developed to infer the energy content of a relativistic-electronbeam-heated plasma column from global or local magnetic field measurements. Under this model, magnetic signals are interpreted in terms of the propagation of macroscopic magnetosonic waves, and differences in characteristics such as beam duration, probe position, and pulse shape, etc., can be distinguished. This model applies to experimental regimes where the commonly used static model becomes invalid.

• Received 9 September 1976

DOI:https://doi.org/10.1103/PhysRevLett.38.704