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A numerical method for the time evolution of systems described by Liouville type equations is derived. The algorithm uses a lattice of numerical markers, which follow exactly Hamiltonian trajectories, to represent the operator d/dt in moving (ie Lagrangian) coordinates. However, nonconservative effects such as particle drag, creation and annihilation are allowed in the evolution of the physical distribution function, which is itself represented according to a delta f decomposition. Further, the method is shown to be ideally suited to the study of a general class of systems involving the resonant interaction of energetic particles with plasma waves. Detailed results are presented for the classic bump on tail problem, for which the algorithm yields exceptionally smooth, low noise evolution of wave energy, especially in the linear regime. Phenomena associated with the nonlinear regime are also described.

Additional information

Authors: CANDY J, JET Joint Undertaking, Abingdon, Oxon (GB)
Bibliographic Reference: Report: JET-P(95)56 EN (1995) 20pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (GB)
Record Number: 199610164 / Last updated on: 1996-03-01
Original language: en
Available languages: en