Plasma Formation, Evolution, and Dynamics in 100-1000 TW Vacuum-Transmission-Line Post-Hole Convolutes

Summary form only given. Vacuum post-hole convolutes are a critical component in present and future high-power z-pinch drivers. A post-hole convolute is used to join several transmission lines in parallel, transferring the combined currents to a single transmission line attached to a load. Magnetic insulation is lost at positions inside the convolute due to the formation of magnetic-field nulls. Electron sheath-current losses in the convolute region of transmission lines have been explored previously. As power levels for planned z-pinch facilities are increased, the formation of electrode plasmas represents an additional potential power-flow loss mechanism. The 3D particle-in-cell code LSP is being used to study the dynamics of electrode plasmas in post-hole convolutes. The simulations use an implicit field-solver and particle advance for modeling the evolution of the dense plasmas. Simulations of the Z accelerator double-post-hole convolutes and load region that include cathode-and anode-plasma formation in the vicinity of the convolute are being conducted. Potential electrical power loss in this region due to the presence of these plasmas is estimated. In addition, simulations of triple-post-hole convolute designs supporting future z-pinch accelerators are also in progress. Available results will be presented.