Improved Design of the VASIMR Radio Frequency Transmission Line

The proposed Phase I work addresses the subtopic ldquo;High-Temperature, High-Voltage Electric Propulsion Harnesses Connectors and Cablesrdquo; and aims to deliver an improved design of the VASIMRreg; ldquo;Rhino Horn,rdquo; the low impedance section of the enginersquo;s 2nd stage RF transmission line. Lying deep in the rocket core assembly, this component carries the largest fraction of the RF power. The Rhino Horn must withstand kV-level reactive voltages and be actively cooled to remove hundreds of watts of Joule self-heat and additional heat conducted from its proximity to the rocket core. Three generations of Rhino Horns have preceded the proposed design, each improving over the previous one. Generation-3 (Gen-3), the most recent operational design, enabled the VX-200SStrade; VASIMRreg; prototype to demonstrate, in July of 2021, thermal steady state at 80 kW in an endurance test lasting 88 continuous hours. The fourth generation (Gen-4) Rhino Horn presented here, features innovations in thermal management, high-voltage insulation, integrated manufacturing and ease of assembly and installation. In this proposal we aim to complete the Gen-4 Rhino Horn design to Critical Design and validate its assumptions in a sub-scale Rhino Horn experimental assembly to be built and tested in vacuum. Also, a numerical ldquo;twinrdquo; of the Gen-4 Rhino Horn will be developed, validated with the experimental results, and used to predict the thermal behavior of the Gen-4 Rhino Horn at power levels gt; 100 kW. While the proposed work focuses on Rhino Horn improvements, the innovation is systemic and relevant to the low impedance RF line driving the first stage ldquo;ionizerrdquo; as well. That section has not exceeded thermal limits at the power levels explored thus far; however, being also a high current-carrying component, it is likely to do so at higher rocket power when the system demands more from the ldquo;ionizerrdquo;. Like the Rhino Horn, the Helicon RF line must maintain insulator integrity to kilovolt potentials in a cramped space. nbsp;