Ionization within a Plasma for the Purpose Investigating Space Propulsion and the Vasimr Plasma Rocket Engine A project present to The Faculty of the Department of Aerospace Engineering San Jose State University in partial fulfillment of the requirements for the degree Master of Science in Aerospace Engineering By Jeffrey Meadows May, 2016 approved by Dr. Marcus Murbach Faculty Advisor Abstract This paper investigates 2 key methods of ionization; Electron bombardment and RF bombardment, for plasma production in space as it relates to propulsion applications. The Paschen curve for air was measured experimentally and a 2mm wide region of <10% error was measured from those results. Ionization costs of between 8,000 and 15,000 electron Volts were calculated within the 2mm gap region. From these results, it was determined that electron bombardment could not provide efficient ionization for thrusting applications above 0.1 Newtons. From previously published data the ratio of ionization potential to atomic mass was a determined to be a key design parameter limiting propellant selection to the noble gases. The elements specifically investigated were Argon, Xenon & Krypton. More importance was placed on investigating Argon owing to the abundance of previously published data. Furthermore, a novel solution was proposed relying on published data and experimental investigation, to fill the design space between VASIMR and ion/hall thrusters. The theoretical results of this solution are a thrust of 0.6 N operating on 25 kW of power at total efficiency of just 10%. A future experiment was proposed for investigating RF bombardment ionization efficiencies of the 3 elements to better estimate their ionization efficiencies within the Helicon antenna to improve this 10% total efficiency. Table of Contents Page 1 Introduction ........................................................................................................... 1. ............................... 8 Background ........................................................................................................... 2. ................................ 9 Brief History of 2. Rocketry ............................................................................................................. 1 1 ...... 0 Space Propulsion .............................................................................................................. 1 3. ................... 6 Rocket 3. propulsion ......................................................................................................... 1 1 .............. 6 Chemical 3.Propulsion ........................................................................................................... 1 2 .............. 7 3.2.1 Solids, liquids & 1 hybrids ............................................................................................................. 8 3.2.2 The Aerospike 2 nozzle ................................................................................................................. 0 Nuclear 3.Propulsion ........................................................................................................... 2 3 ................. 1 Electric 3.propulsion ........................................................................................................... 2 4 ................. 2 3.4.1 The Ion thruster ................................................................................................................. 2 ........ 2 VASIMR Engine ................................................................................................................... 2 4. ................. 5 4.1 Plasma .................................................................................................................... 2 ........................... 6 4.2 Components of the VASIMR 2 engine .................................................................................................. 7 4.2.1 Propellant Ionization ............................................................................................................... 2 ... 7 4.2.2 Ion Cyclotron Resonance Heating 2 (ICRH) ................................................................................... 8 4.2.3 Plasma acceleration within an expanding magnetic 2 field .......................................................... 9 Design Iterations on 3 5. VASIMR .............................................................................................................. 1 5. VASIMR iteration VX- 3 1 10 .................................................................................................................... 1 5. VASIMR iteration VX- 3 2 50 .................................................................................................................. 3 5.3 VASIMR iteration VX- 3 200 .................................................................................................................. 5 5.4 Mars Mission profile utilizing VASIMR 3 engines ................................................................................ 9 Theory ................................................................................................................... 4 6. .............................. 1 6. Ionization methods & Electro- 4 1 magnetism ........................................................................................ 1 6.2 RF bombardment ......................................................................................................... 4 ..................... 2 6.3 Electron bombardment ......................................................................................................... 4 ............ 3 6.3.1 Ionization cost ....................................................................................................................... 4 ..... 4 6.4 Paschen’s law .......................................................................................................................... 4 .......... 4 6. Electro-magnetism & electro-magnetic 4 5 interaction ......................................................................... 6 6.5.1 Trapping charged particles in a mirrored magnetic 4 field ........................................................... 8 Experiment: Ionization Cost and Voltage breakdown in air at Sea 5 7. Level ........................................... 0 7. Investigation of ionization cost in standard 5 1 atmosphere ................................................................. 0 7.Results ................................................................................................................ 5 2 ............................... 3 2 7. Discussion........................................................................................................... 5 3 ............................... 5 8 Electromagnetism ................................................................................................. 5 . .............................. 6 8. Investigation of charged particle trapping within the ICRH of VASIMR 1 modeled by a uniform magnetic field ......................................................................................................................... 5 ................ 6 8. Investigation of charged particle trapping in a non-uniform magnetic field 5 2 BOOM ........................ 8 Novel 9 Design ................................................................................................................... 6 . .................... 3 9.1 Purpose ................................................................................................................... 6 .......................... 3 9. Novel Solution Design 6 2 Analysis ......................................................................................................... 3 9. Mission profile Design 6 3 process ......................................................................................................... 5 Novel solution 9.comparison ......................................................................................................... 6 4 ...... 5 9.4.1 Propellant selection ................................................................................................................ 6 ... 6 9.4.2 Design ................................................................................................................... 6 ...................... 6 9.4.3 Solution ................................................................................................................. 6 ..................... 6 Conclusive Remarks ............................................................................................................ 6 10. ............ 8 10.1 Project Conclusion ............................................................................................................... 6 ........... 8 10.2 Future Plans ....................................................................................................................... 6 ............. 9 Citations ........................................................................................................... 6 11. ............................... 9 3 Table of Figures Figure 2.1 Chinese “arrows of flying fire”, such as might be expected to have been used at the battle of Kai-Keng. .................................................................................................................................. 10 Figure 2.2 (left); Sir Isaac Newtown [24] .................................................................................................................................