AbstractThe objective of the present paper is to study the behaviour of a travelling wave direct energy converter which is supposed to convert the energy of fusion proton ions produced in a FRC D–3He fusion plasma. Numerical experiments with a one and two-dimensional approximation give the following results: (1) an external circuit has been proposed for the travelling wave, and time-dependent, one-dimensional computations of the momentum conservation equation together with Poisson’s equation have been carried out, resulting in autonomous oscillation of the travelling wave. About 72.3% conversion efficiency has been obtained with a grid voltage of 1.0 MV. (2) With a two-dimensional approximation, the efficiency and grid voltage with newly proposed cylindrical grids result in 65.5% and 1.7 MV when the collision loss with the grids is neglected, while 54.7% and 1.4 MV are obtained when the collision loss is included.