Propagating Magnetic Wave Plasmoid Accelerator
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Propagating Magnetic Wave Plasmoid Accelerator Jedediah M. Smith, Matthew J. Bartone, Andrew J. Greenlee, John T. Slough University of Washington; Aeronautics and Astronautics Department; Plasma Dynamics Lab; Seattle, WA 98195 Plasma Creation Arc gun (8eV, 10 20 part/m 3 ) Helicon pre-ionization (10eV, 10 20 part/m 3 ) Second half cycle ionization Vacuum System Fused silica tube (Rotosil) One meter diameter stainless steel dump chamber 1200 1/s magnetic-levitation turbo pump Base pressure in the low 10 -8 torr High Velocity Plasma Accelerator Possible applications: High power electric propulsion in space New approach to high density fusion Fueling Source for ITER and Tokamaks Combining plasmoid creation with efficient pulsed magnetic wave acceleration No electrodes or grids to corrode Can be operated over a wide range of exhaust velocities and propellant masses Exit velocities >200km/s for plasmoid masses of ~0.1mg are anticipated With a 10kHz repetition rate an output of 30MW could be achieved Control and Data Acquisition LabView control and automation programming Fiber Ethernet isolated LabJack for analog and logic control of high voltage CAMAC DSP transient digitizers (8bit, 10MHz) Timing and control via fiber out of CAMAC Jorway 221 and 222 modules Construction Plasma Acceleration Individually controlled high speed coils (eight total) Low inductance strip-line feed from caps to coils Integral bias field Ignitron switching 25kV, 100kA Copper flux shaper on drift and diagnostic region Double Pass HeNe Mach-Zender 40MHz Bragg cell High stability from damped, isolated single optics table Triple Tip Langmuir Probe Six foot length for axial studies Integral Magnetic Probes Arranged in sets consisting of: One total flux sensing loop One hair-pin flux density loop End-On Optical Access Refurbished Spex Spectrometer 16 channel PMT 0.28 Å resolution Wavelengths from soft UV to NIR Diagnostics Summary Charge/Dump Resistor Ignitron Capacitor Strip-line Assembly Internal Top-Hats Integral Bias Feed Abstract A high-velocity plasma accelerator utilizing a Propagating Magnet Wave (PMW) has been designed and constructed that is directly applicable to space propulsion as well as to new innovative high energy density approaches towards fusion. The PMW plasmoid accelerator also has possible applications as a fueler for future fusion reactors such as the international fusion reactor, ITER, as well as current tokamak experiments for adding rotational momentum and velocity shear for enhanced stability and transport control. The natural application for the PMW accelerator is for high power electric propulsion in space. For this purpose the PMW is employed as a pulsed thruster that operates naturally at both high power and efficiency with no need for electrodes or grids. Operational parameters can be varied over a wide range in both exhaust velocity and propellant mass. To efficiently accelerate plasmoids to high velocities an acceleration method other than the simple tapered coil must be employed. In these experiments, the rapid acceleration of a compact plasmoid is realized through the application of an externally applied propagating magnetic field. Here, the large axial JxB force is generated from the induced azimuthal current inside the plasmoid and the radial component of the external, axially propagating magnetic field. This accelerating force is sustained as long as the plasmoid remains in phase with the wave field. Exit velocities greater than 200 km/sec for plasmoid masses on the order of 0.1 mg are anticipated from the device that is currently being tested, and the results from the initial experiments will be presented. This research is being supported by the U.S. Air Force Research Laboratory, Edwards AFB. Gas Diffusion Nozzle Alumina Shielding Tube Bias Coil Windings Floating Molybdenum Washers Alumina Housing Brass Assembly Nut Gas Feed Tube Molybdenum Cathode Boron Nitride Insulation Washers Molybdenum Anode Copper Andode Return & Assembly Tube time (μsec) time (μsec) 0 60 120 180 240 V FRC (km/s) 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 0.02 0.04 0.06 0.08 0.1 M (mg) 0 15 30 45 60 75 90 Average Ti T i (eV) 0 1 2 3 4 5 6 7 8 9 0 0.3 0.6 0.9 1.2 Total FRC thermal energy E Th (kJ) 0 1 2 3 4 5 6 7 8 9 Equilibrium Relations: 2 s r 0 2 0 x 1 dr B P 2 2 1 s - = μ = β ∫ ( 2 s vac ext x 1 B B - = 0 2 ext 0 0 2 B kT n P μ = = Radial Pressure Balance Axial Pressure Balance Flux conservation EXTERNAL FIELD FRC CLOSED POLOIDAL FIELD Field Reversed Configuration Geometry Predicted results from MHD (Moqui) modeling LabView experiment control software Digitizer rack 25kV, 14 uF capacitors Integral bias supply/emergency stop button Strip-line assembly Arc gun Helicon pre-ionization Arc gun Fused silica tube HeNe interferometer Flux pickup loops Plasma shot Arc gun test shot (view down tube)
Transcript of Propagating Magnetic Wave Plasmoid Accelerator
Propagating Magnetic Wave Plasmoid AcceleratorJedediah M. Smith, Matthew J. Bartone, Andrew J. Greenlee, John T. Slough
University of Washington; Aeronautics and Astronautics Department; Plasma Dynamics Lab; Seattle, WA 98195
Plasma CreationArc gun (8eV, 1020 part/m3)
Helicon pre-ionization (10eV, 1020 part/m3)
Second half cycle ionization
Vacuum SystemFused silica tube (Rotosil)
One meter diameter stainless steel dump chamber
1200 1/s magnetic-levitation turbo pump
Base pressure in the low 10-8 torr
High Velocity Plasma Accelerator
Possible applications:
High power electric propulsion in space
New approach to high density fusion
Fueling Source for ITER and Tokamaks
Combining plasmoid creation with efficient pulsed magnetic wave acceleration
No electrodes or grids to corrode
Can be operated over a wide range of exhaust velocities and propellant masses
Exit velocities >200km/s for plasmoid masses of ~0.1mg are anticipated
With a 10kHz repetition rate an output of 30MW could be achieved
Control and Data AcquisitionLabView control and automation programming
Fiber Ethernet isolated LabJack for analog and logic control of high voltage
CAMAC DSP transient digitizers (8bit, 10MHz)
Timing and control via fiber out of CAMAC Jorway 221 and 222 modules
Construction
Plasma AccelerationIndividually controlled high speed coils (eight total)
Low inductance strip-line feed from caps to coils
Integral bias field
Ignitron switching 25kV, 100kA
Copper flux shaper on drift and diagnostic region
Double Pass HeNe Mach-Zender40MHz Bragg cell
High stability from damped, isolated single optics table
Triple Tip Langmuir ProbeSix foot length for axial studies
Integral Magnetic ProbesArranged in sets consisting of:
One total flux sensing loop
One hair-pin flux density loop
End-On Optical Access
Refurbished Spex Spectrometer16 channel PMT
0.28 Å resolution
Wavelengths from soft UV to NIR
Diagnostics
Summary
Charge/Dump Resistor
Ignitron
Capacitor
Strip-line Assembly
Internal Top-Hats
Integral Bias Feed
AbstractA high-velocity plasma accelerator utilizing a Propagating Magnet Wave
(PMW) has been designed and constructed that is directly applicable to space propulsion as well as to new innovative high energy density approaches towards fusion. The PMW plasmoid accelerator also has possible applications as a fueler for future fusion reactors such as the international fusion reactor, ITER, as well as current tokamak experiments for adding rotational momentum and velocity shear for enhanced stability and transport control.
The natural application for the PMW accelerator is for high power electric propulsion in space. For this purpose the PMW is employed as a pulsed thruster that operates naturally at both high power and efficiency with no need for electrodes or grids. Operational parameters can be varied over a wide range in both exhaust velocity and propellant mass. To efficiently accelerate plasmoids to high velocities an acceleration method other than the simpletapered coil must be employed. In these experiments, the rapid acceleration of a compact plasmoid is realized through the application of an externally applied propagating magnetic field. Here, the large axial JxB force is generated from the induced azimuthal current inside the plasmoid and the radial component of the external, axially propagating magnetic field. This accelerating force is sustained as long as the plasmoid remains in phase with the wave field. Exit velocities greater than 200 km/sec for plasmoid masses on the order of 0.1 mg are anticipated from the device that is currently being tested, and the results from the initial experiments will be presented.
This research is being supported by the U.S. Air Force Research Laboratory, Edwards AFB.
Gas Diffusion Nozzle
Alumina Shielding Tube
Bias Coil Windings
Floating Molybdenum Washers
Alumina Housing
Brass Assembly Nut
Gas Feed Tube
Molybdenum Cathode
Boron Nitride Insulation Washers
Molybdenum Anode
Copper Andode Return& Assembly Tube
time (µsec) time (µsec)
0
60
120
180
240
VFRC
(km/s)
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 90
0.02
0.04
0.06
0.08
0.1
M
(mg)
0
15
30
45
60
75
90 Average Ti
Ti
(eV)
0 1 2 3 4 5 6 7 8 90
0.3
0.6
0.9
1.2Total FRC thermal energy
ETh
(kJ)
0 1 2 3 4 5 6 7 8 9
EquilibriumRelations:
2s
r
020 x1dr
BP2
2
1s
−=µ
=β ∫
( )2s
vacext x1
BB
−=
0
2ext
00 2B
kTnPµ
== Radial Pressure Balance
Axial PressureBalance
Flux conservationEXTERNAL
FIELDFRC CLOSED
POLOIDAL FIELD
Field Reversed Configuration Geometry
Predicted results from MHD (Moqui) modelingLabView experiment control software
Digitizer rack
25kV, 14 uF capacitorsIntegral bias supply/emergency stop button
Strip-line assembly
Arc gun
Helicon pre-ionization
Arc gun
Fused silica tube
HeNe interferometer
Flux pickup loops
Plasma shot
Arc gun test shot (view down tube)
