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© Copyright 2016 Evan G. Carroll © Copyright 2016 Evan G. Carroll Driving Flows in Laboratory Astrophysical Plasma Jets: The Mochi.LabJet Experiment Evan G. Carroll A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Aeronautics & Astronautics University of Washington 2016 Committee: Setthivoine You Ray Golingo Program Authorized to Offer Degree: Aeronautics & Astronautics University of Washington Abstract Driving Flows in Laboratory Astrophysical Plasma Jets: The Mochi.LabJet Experiment Evan G. Carroll Chair of the Supervisory Committee: Assistant Professor Setthivoine You William E. Boeing Department of Aeronautics & Astronautics Mochi.Labjet is a new experiment at the University of Washington developed to investigate the interaction of shear flows in plasma jets with boundary conditions similar to an accretion disc system. This thesis details the engineering design and first plasmas of the Mochi.Labjet experiment. The experiment required construction of a new three electrode plasma gun with azimuthal symmetric gas injection, two optically-isolated pulsed power supplies for generating and sustaining plasma, and one optically-isolated pulsed power supply for generating a background magnetic field. Optical isolation is achieved with four custom circuits: the TTL-optical transmitter, optical-TTL receiver, optical-relay, and optical-tachometer circuits. First plasmas, during the commissioning phase of the apparatus, show evidence of flared jet structures with significant azimuthal symmetry. Table of Contents List of Figures ................................................................................................................................ iii Chapter 1 - Introduction .................................................................................................................. 1 1.1 Astrophysical Jets in the Laboratory ..................................................................................... 2 1.2 The Mochi.Labjet Experiment .............................................................................................. 6 1.2.1 The Mochi.LabJet Plasma Gun ...................................................................................... 7 1.2.2 Gun Electrode Pulsed-Power Supply Unit ..................................................................... 8 1.2.3 Magnetic Field Pulsed-Power Supply Unit .................................................................. 10 Chapter 2 - Mochi.LabJet Plasma Gun ......................................................................................... 12 2.1 Inner Electrode .................................................................................................................... 13 2.2 Middle Electrode ................................................................................................................. 14 2.3 Outer Electrode ................................................................................................................... 16 2.4 Gas Plume Model ................................................................................................................ 17 Chapter 3 – Electrode Power Supply Units .................................................................................. 19 3.1 High Speed Power Electronics ............................................................................................ 19 3.2 Mochi.LabJet PSU2 and PSU3 Overview........................................................................... 21 3.3 Custom Ignitron Tower ....................................................................................................... 23 3.4 Circuit Simulation ............................................................................................................... 27 3.5 Low Voltage Optically-Isolated Control Electronics .......................................................... 30 i 3.5.1 TTL-Optical Transmitter Circuit .................................................................................. 31 3.5.2 Optical-TTL Receiver Circuit ...................................................................................... 32 3.5.3 Optical-Relay Circuit .................................................................................................... 34 3.5.4 Optical-Tachometer Circuit .......................................................................................... 36 Chapter 4 – First Plasmas ............................................................................................................. 39 4.1 Flared Plasma Jet ................................................................................................................. 39 4.2 The Bundt Cake Formation ................................................................................................. 43 Chapter 5 – Conclusion ................................................................................................................. 45 Bibliography ................................................................................................................................. 47 Appendix A – Mochi.LabJet.Gun ................................................................................................. 49 A.1 Mochi.Labjet.Gun Assembly ............................................................................................. 49 A.2 Mochi.LabJet.Gun Inner Electrode Assembly ................................................................... 51 A.3 Mochi.LabJet.Gun.MiddleElectrode Assembly ................................................................. 53 A.4 Mochi.LabJet.Gun.Outer.Electrode Assembly................................................................... 55 A.4.1 Mochi.LabJet.Gun.OuterElectrode.InnerPlenum Assembly ....................................... 57 A.4.2 Mochi.LabJet.Gun.OuterElectrode.OuterPlenum Assembly ....................................... 59 Appendix B – Mochi.LabJet.PSU ................................................................................................. 61 B.1 Mochi.LabJet.PSU.IgnitronTower .................................................................................. 61 B.2 Mochi.LabJet.PSU.CapacitorBank Assembly ................................................................ 63 ii List of Figures Figure 1 – Radio Galaxy Cygnus A. ............................................................................................... 1 Figure 2 – Boundary Conditions of an Astrophysical Jet. .............................................................. 4 Figure 3 – Caltech Plasma Evolution.............................................................................................. 5 Figure 4 – Three Electrode Plasma Gun Configuration (Chapter 2). ............................................. 7 Figure 5 – Curves of Paschen’s Law for Select Gases. .................................................................. 9 Figure 6 – The Mochi.LabJet Plasma Gun. .................................................................................. 12 Figure 7 – Inner Electrode Assembly. .......................................................................................... 13 Figure 8 – Inner Electrode Gas Injection. ..................................................................................... 14 Figure 9 – The Middle Electrode Assembly. ................................................................................ 15 Figure 10 – Middle Electrode Gas Injection. ................................................................................ 15 Figure 11 – Outer Electrode Assembly. ........................................................................................ 16 Figure 12 – Gas Plume Model. ..................................................................................................... 18 Figure 13 – Gun Electrode Power Supply Circuit Diagram. ........................................................ 22 Figure 14 – Gun Electrode Power Supply Unit. ........................................................................... 23 Figure 15 – Gun Electrode Power Supply Capacitor Bank and Custom Ignitron Tower. ............ 24 Figure 16 – PSU QUCS Circuit Simulation. ................................................................................ 27 Figure 17 – Plot of PSU QUCS Simulation Output. ..................................................................... 30 Figure 18 – TTL-Optical Transmitter Circuit. .............................................................................. 32 Figure 19 – Optical-TTL Receiver Circuit. .................................................................................. 33 Figure 20 – Optical-TTL Reciever Circuit Switching Times. ...................................................... 34 Figure 21 – Optical-Relay Circuit................................................................................................. 35 Figure 22 – Optical-Relay Switching Times. ............................................................................... 36 iii Figure 23 – Optical-Tachometer Circuit. ...................................................................................... 37 Figure 24 – Optical-Tachometer Circuit Performance. ................................................................ 38 Figure 25 – Votlage Traces for Shots 3080-3091. ........................................................................ 39 Figure 26 – Current Traces for Shots 3080-3091. ........................................................................ 40 Figure 27 – Time Evolution of Flared Plasma Jet. ......................................................................
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