A5085244942- Plasma Diagnostics and Applications
- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Electrohydrodynamics and Fluid Dynamics
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Superconducting Materials and Applications
- Fusion materials and technologies
- Laser-induced spectroscopy and plasma
- Rocket and propulsion systems research
- Space Satellite Systems and Control
- Dust and Plasma Wave Phenomena
- Spacecraft and Cryogenic Technologies
- Gas Dynamics and Kinetic Theory
- Gyrotron and Vacuum Electronics Research
- Electromagnetic Launch and Propulsion Technology
- Laser-Plasma Interactions and Diagnostics
- Magnetic Field Sensors Techniques
- Underwater Vehicles and Communication Systems
- Advanced Sensor Technologies Research
- Nuclear Physics and Applications
- Advanced Data Storage Technologies
- Cavitation Phenomena in Pumps
- Planetary Science and Exploration
General Atomics (United States)
1995-2025
University of Illinois Urbana-Champaign
2024
Illinois College
2024
Atmospheric and Space Technology Research Associates (United States)
2007-2020
University of Houston
2003-2009
Johnson Space Center
1997-2005
The University of Texas at Austin
2003
Oak Ridge National Laboratory
2003
National Aeronautics and Space Administration
2002
Massachusetts Institute of Technology
1987-1998
The helicon plasma stage in the Variable Specific Impulse Magnetoplasma Rocket (VASIMR®) VX-200i device was used to characterize an axial potential profile within expanding magnetic nozzle region of laboratory based device. ion acceleration mechanism is identified as ambipolar electric field produced by electron pressure gradient, resulting a local speed Mach 4 downstream nozzle. A 20 eV argon kinetic energy measured source, which had peak strength 0.17 T. source operated with 25 mg s−1...
Understanding the physics involved in plasma detachment from magnetic nozzles is well theorized, but lacking large scale experimental support. We have undertaken an experiment using 150-m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> variable specific impulse magnetoplasma rocket test facility and VX-200 thruster seeking evidence that occurs understanding of physical processes involved. It was found jet this does indeed detach applied...
A new frequency-stepped Doppler backscattering (DBS) system has been integrated into a real-time steerable electron cyclotron heating launcher to simultaneously probe local background turbulence (f &lt; 10 MHz) and high-frequency (20–550 density fluctuations in the DIII-D tokamak. The allows for 2D steering (horizontally vertically) over wide angular ranges optimize location wavenumber response. vertical can be optimized during discharge real time. DBS employs programmable frequency...
The ability to obtain high plasma densities with fractional ionization using readily available, low-cost components makes the helicon a candidate source for many applications, including rocket propulsion, fusion component testing, and materials processing. However, operation of can be sensitive function magnetic field strength geometry as well driving frequency, especially when light feedstock gases such hydrogen or helium. In this paper, results from coupled rf transport model are compared...
The VAriable Specific Impulse Magnetoplasma Rocket (VASIMR®) is a high power electric spacecraft propulsion system, capable of Isp/thrust modulation at constant [F. R. Chang Díaz et al., Proceedings the 39th AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, 8–11 Jan. 2001]. VASIMR® uses helicon discharge to generate plasma. This plasma energized by an rf booster stage that left hand polarized slow mode waves launched from field side ion cyclotron resonance. In experiments reported in...
H IGH-POWER electric propulsion thrusters can reduce propellant mass for heavy-payload orbit-raising missions and cargo to the moon near-Earth asteroids, they trip time of robotic piloted planetary [1–4]. The Variable Specific Impulse Magnetoplasma Rocket (VASIMR®) VX-200 engine is an system capable processing power densities on order 6 MW=m with a high specific impulse (4000 6000 s) inherent capability vary thrust at constant power. potential long lifetime due primarily radial magnetic...
A mechanism for ambipolar ion acceleration in a magnetic nozzle is proposed. The plasma adiabatic (i.e., does not exchange energy with its surroundings) the diverging section of so any lost by electrons must be transferred to ions via electric field. Fluid theory indicates that change potential proportional average electron energy. These predictions were compared measurements VX-200 experiment which has conditions conducive acceleration. planar Langmuir probe was used measure potential,...
The accuracy of a plasma impact force sensor was compared with that the more commonly used inverted pendulum thrust stand using 5 kW Xe Hall effect thruster.An improved momentum flux designed and constructed based on previous design.Real-time measurements were made both stand.The measured exerted onto it by thruster exhaust plume resolution 0.1 mN an average discrepancy 2% measurements.Experiments completed 9 m 6 cylindrical vacuum chamber.The total from modulated 34 to 356 varying anode...
Testing of the Variable Specific Impulse Magnetoplasma Rocket VX-200 engine was performed over a wide throttle range in vacuum chamber with sufficient pumping to permit exhaust plume measurements at argon background pressures less than during firings, ensuring charge-exchange mean free paths longer chamber. Measurements plasma flux, radio frequency power, propellant flow rate, and ion kinetic energy were used determine ionization cost krypton helicon discharge. Experimental data on cost,...
Helicon current drive (CD), also called fast wave CD in the lower hybrid range of frequencies, has long been regarded as a promising tool for reactor grade plasmas.A newly installed MW-level system at DIII-D will be first test this technology reactor-relevant plasmas, sense that full single-pass absorption is expected.A 30-module traveling antenna and optimized in-vessel early 2020.The linear electromagnetic characteristics unloaded module array have extensively tested both on bench vessel...
The development of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) was initiated in late 1970s to address a critical requirement for fast, high-power interplanetary space transportation. While not being fusion rocket, it nevertheless borrows heavily from that technology and takes advantage natural topology open-ended magnetic systems. In addition its high power density exhaust velocity, VASIMR is capable constant throttling feature, which allows in-flight mission-optimization...
Detachment of the plasma exhaust is an essential element a magnetic nozzle operation that requires experimental, analytic and computer simulation studies. The present work devoted to simulations detachment in Variable Specific Impulse Magnetoplasma Rocket. Both particle MHD methods have been used results are reported this paper.
The momentum distribution of the current carrying suprathermal electrons is determined from measurement X-mode transmission near fundamental cyclotron frequency during inductive and radiofrequency drive in Versator II tokamak. Measurement differential attenuation radiation two beams with finite opposite parallel index refraction N( allows separation wave due to absorption that non-resonant mechanisms. It shown such measurements can be used determine part which antisymmetric p1 i.e. Fa(p1) ≡...
Decay waves have been observed in the megahertz range helium plasma generated by variable specific impulse magnetoplasma rocket thruster. They are measured using one of tips a triple probe connected to 50 Ω input spectrum analyzer via dc block (a small capacitor). The maximum amplitude all is center and does not appear correlated radial electron density or temperature profiles. seem be close helicon antenna that was 91 cm “upstream” from measuring Langmuir probe. A possible explanation...
Excitation, propagation, and absorption of directly launched ion Bernstein waves were studied with ${\mathrm{CO}}_{2}$ laser scattering in the Alcator C tokamak. Optimum excitation is obtained when an ion-cyclotron harmonic layer located just behind antenna. Wave at \ensuremath{\omega}=3${\ensuremath{\Omega}}_{\mathrm{D}=1.5{\ensuremath{\Omega}}_{\mathrm{H}}}$ was observed. 3 It may be necessary to control edge density fluctuation level order minimize optimize heating.
Abstract More than 0.6 MW of rf power at 476 MHz has been coupled to DIII-D plasmas by launching helicon (whistler) waves with a traveling-wave antenna (comb-line) in the fast-wave polarization (Van Compernolle et al 2021 Nucl. Fusion 61 116034) which resulted observation electron heating core plasma single-pass absorption based on ray-tracing L-mode discharges. The coupling performance 1.5 m wide 30-element comb-line consistent expectations 2015–2016 experiments low-power 12-element...
In the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) radio frequency (rf) waves both produce plasma and then accelerate ions. The production is done by action of helicon waves. These are circular polarized in direction electron gyromotion. ion acceleration performed cyclotron resonant (ICRF) acceleration. Advanced Space Propulsion Laboratory (ASPL) actively developing efficient ICRF VASIMR experimental device at ASPL called VX-10. It configured to demonstrate 10kW level support a...
It is shown that in tokamak plasmas sustained by rf current drive, the contribution of suprathermal rf-driven electron population to poloidal beta (${\ensuremath{\beta}}_{p}$) can be substantial if total comparable Alfv\'en critical current, ${I}_{A}$=(4\ensuremath{\pi}mcv/${\ensuremath{\mu}}_{0}$ec)\ensuremath{\gamma}. Equilibria with values \ensuremath{\epsilon}${\ensuremath{\beta}}_{p}$ up approximately 1.3 were obtained, and no equilibrium or gross stability limits observed.
The Advanced Space Propulsion Laboratory (ASPL) of NASA's Johnson Center is performing research on a Variable Specific Impulse MagnetoPlasma Rocket (VASIMR). VASIMR high power, radio frequency (RF) driven magnetoplasma rocket, capable very exhaust velocities, > 100 km/s. A NASA-led team involving industry, academia and government facilities pursuing the development this concept in United States. ASPL's experimental focuses three major areas: helicon plasma production, ion cyclotron resonant...