Current transport and loss mechanisms in the Z accelerator

• Published in: Physical review. Accelerators and beams Vol. 22; no. 12; p. 120401
• Main Authors: Bennett, N., Welch, D. R., Jennings, C. A., Yu, E., Hess, M. H., Hutsel, B. T., Laity, G., Moore, J. K., Rose, D. V., Peterson, K., Cuneo, M. E.
• Format: Journal Article
• Language: English
• Published: College Park American Physical Society 10-12-2019; American Physical Society (APS)
• Subjects: Current density; Current loss; Electrodes; Electron density; Insulation; Kelvin-Helmholtz instability; PARTICLE ACCELERATORS; Particle emission; Plasmas (physics); Pulse propagation; Transmission lines
• ISSN: 2469-9888; 2469-9888
• DOI: 10.1103/PhysRevAccelBeams.22.120401

A challenge for the TW-class accelerators drivingZ-pinch experiments, such as Sandia National Laboratories’Zmachine, is to efficiently couple power from multiple storage banks into a single multi-MA transmission line. The physical processes that lead to current loss are identified in new large-scale, multidimensional simulations of theZmachine. Kinetic models follow the range of physics occurring during a pulse, from vacuum pulse propagation to charged-particle emission and magnetically-insulated current flow to electrode plasma expansion. Simulations demonstrate that current is diverted from the load through a combination of standard transport (uninsulated charged-particle flows) and anomalous transport. Standard transport occurs in regions where the electrode current density is a few104−105A/cm2and current is diverted from the load via transport without magnetic insulation. In regions with electrode current density>106A/cm2, electrode surface plasmas develop velocity-shear instabilities and a Hall-field-related transport which scales with electron density and may, therefore, lead to increased current loss.