Propagation of intense plasma and ion beams across B-field in vacuum and magnetized plasma

摘要

This paper summarizes experimental results on the injection and transport of intense, wide cross-section H+ plasma (PB), and ion beams (IB), in vacuum and ambient H+ plasma across an applied B-field. The injection of plasma and ion beams into magnetic confinement devices have the potential to heat and support current in these systems (e.g., field-reversed configurations). The translational energies of the PB and IB ranged between E-pb = 60 to 120 eV and E-IB = 60 to 120 keV, with temperatures and densities in the range of T-b similar to 2 to 10 eV, n(b) similar to 10(12) to 10(13) cm(-3), and T-b similar to 200 eV, n(b) 10(10) to 10(11) cm(-3), respectively. Compared to earlier studies (Peter, 1979; Wessel et al., 1988, 1990), this research extends the experimental parameter space to higher beam current densities (up to 30 A/cm(2)) and higher B-field strengths up to 1.6 kG. The PB and IB were both about 10 cm in diameter at the injection port, and the ratio of beam specific energy to ambient B-field specific energy,,B, was in the range of 0.1 to 10. Ratios of beam Larmor radius to beam size, p, ranged from 10(-1) to 1 and 1 to 10 for the PB and IB, respectively. Cross B-field propagation of the PB in vacuum was undeflected as a whole with a sharp increase (one order or more) in the current density of the central beam core at B-field levels > 1 kG accompanied by a significant loss of beam peripheral layers, beam "braking" and preferential beam expansion along the B-field lines. Cross B-field propagation of the PB in ambient plasma did not differ substantially from the case without B-field, that is, no deflection of the PB as a whole, which could be due to an insufficient neutralization of the induced E-field inside the PB. Cross B-field propagation of the IB in ambient plasma followed a single particle trajectory deflection with a simultaneous significant loss of IB intensity without any detectable bunching, indicating an adequate shorting of the polarization E-field inside the IB.