STOPPING POWER OF IONS IN A STRONGLY MAGNETIZED PLASMA

The energy loss of heavy ions in a strongly magnetized plasma is studi ed by means of Vlasov and Particle-in-Cell (PIC) simulations. The topi c is of importance for many practical applications, as for example in the electron cooling of heavy ion beams. Measurements of the longitudi nal cooling force show strong deviations from the well known linear th eories. Moreover, the possibility of heavy ions to reach high charge s tates Z(p) increases the interest in understanding the plasma regime w ith coupling parameter Z(p)/N-D>1 (N-D is the number of electrons in a Debye sphere), when nonlinear phenomena are important. In this regime a linearization of the drift kinetic Vlasov-Poisson system is not pos sible, so that a fully nonlinear numerical approach is unavoidable. Co mparisons between the two numerical schemes are made for the stopping power and the potential created in the plasma by a moving ion, togethe r with the dielectric theory of ion stopping. Our results show strong deviations from the dielectric theory, and our investigations show the importance of the role played by the electrons trapped in the potenti al troughs excited by the ion in the stopping process. (C) 1996 Americ an Institute of Physics.