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starship-design: Plasma Engine (VASIMR)

I found more information on the plasma engine mentioned on CNN.
I knew about VASIMR before, but had not made the connection with Franklin Chang-Diaz. These abstracts may help give a better understanding of his plasma engine. I pointed out to the group once before that much of the research going into VASIMR can also be applied to other concepts such as ACMF that are not as far along.
This device is apparently is in test stand stage (it could be flyable in a few years) while ACMF is in test bed stage. There are also several other approaches such as Dense Plasma Focus, Star Thrust, Inertial Electrostatic Confinement, and the Synchrotron Radiation Drive currently in various stages of testing.
Both VASIMR and ACMF/AIMSTAR offer delta v in the +200km/sec range making them suitable for relatively rapid interplanetary travel.
Mini-conference on Deep Space Plasma Thrusters.
MIXED session, Thursday afternoon, November 20
North 6, Convention Center

[pThpM2.01] Research Status of the Variable Specific Impulse Magnetoplasma Rocket

F. R. Chang-Diaz ((ASPL/JSC/NASA))

Research in the VASIMR approach to high-power rocket propulsion has continued since 1980. The system consists of a three-stage asymmetric magnetic mirror, featuring a hybrid magnetic nozzle. Plasma is injected, heated and subsequently exhausted to provide modulated thrust and specific impulse at constant power. Plasma injector studies initially involve a modified Lorentz Force Accelerator. Other injector concepts, including helicons and hollow cathodes are briefly examined. Plasma heating methodsinvolve electron and ion cyclotron resonance, though other efficiency enhancements such as whistlers and mode coupling are being explored. Plasma detachment dynamics from the magnetic nozzle are considered. In the low temperature, high density regime, the use of a co-axial, hypersonic neutral gas boundary layer near the nozzle throat increases the thrust while triggering collisional plasma detachment. In the high temperature, low density regime, inducing time-dependent magnetic ripples in the nozzle is a potential turbulence-inducing mechanism for plasma detachment. Experimental studies currently focus on plasma injection and heating to power levels of up to 200kW in pulses of several seconds. A diagnostics set characterizes the plasma conditions throughout the system. Performance and advantages over other rocket technologies are presented in the context of a mission to Mars.

[pThpM2.02] A Plasma Diagnostic Set for the Study of a Variable Specific Impulse Magnetoplasma Rocket

J. P. Squire, F. R. Chang-Diaz ((ASPL/JSC/NASA)), R. Bengtson, Jr. Bussell, V. T. Jacobson, A. J. Wootton ((University of Texas at Austin)), E. A. Bering, T. Jack, A. Rabeau ((University of Houston))

The Advanced Space Propulsion Laboratory (ASPL) is developing a Variable Specific Impulse Magnetoplasma Rocket (VASIMR) using an RF heated magnetic mirror operated asymmetrically. We will describe the initial set of plasma diagnostics and data acquisition system being developed and installed on the VASIMR experiment. A U.T. Austin team is installing two fast reciprocating probes: a quadruple Langmuir and a Mach probe. These measure electron density and temperature profiles, electrostatic plasma fluctuations, and plasma flow profiles. The University of Houston is developing an array of 20 highly directional Retarding Potential Analyzers (RPA) for measuring ion energy distribution function profiles in the rocket plume, giving a measurement of total thrust. We have also developed a CAMAC based data acquisition system using LabView running on a Power Macintosh communicating through a 2 MB/s serial highway. We will present data from initial plasma operations and discuss future diagnostic development.

[pThpM2.03] An Injector for the Variable Specific Impulse Magnetoplasma Rocket

T. W. Glover ((Rice University)), F. R. Chang-Diaz, J. P. Squire ((ASPL/JSC/NASA)), A. A. Chan ((Rice University))

We present a summary of progress on the development of a plasma injector for NASA's VASIMR (Variable Specific Impulse Magnetoplasma Rocket) engine. The plasma rocket constrains a flowing plasma in an asymmetric magnetic bottle and exhausts it through a magnetic nozzle to produce thrust. The injector is a plasma source located on the axis of symmetry, forward of the series of coils forming the constraining magnetic field. The injector is intended to produce a well-collimated jet of highly ionized plasma which will enter the central cell of the machine through its forward mirror. The prototype design is based on that of a Lorentz Force Accelerator developed as a thruster by the electric propulsion research group at Princeton. Our investigation focuses on the effects of the rocket's magnetic field on the operation of the injector, the effect of a local magnetic field on the discharge behavior, and the effectiveness of discharge initiation by glow discharge versus initiation by ECRH. We evaluate the performance of this prototype injector by comparing the characteristics of the plasma it inserts into the central cell of the engine with the characteristics called for in the design of the plasma rocket.

[pThpM2.04] ICRF Development for the Variable Specific Impulse Magnetoplasma Rocket

P. M. Ryan ((Oak Ridge National Laboratory)), F. W. Baity, G. C. Barber, M. D. Carter, D. J. Hoffman, E. F. Jaeger, D. J. Taylor ((ORNL)), F. R. Chang-Diaz, J. P. Squire ((ASPL/NASA/JSC)), G. McCaskill ((Lockheed Martin Corporation))

The feasibility of using magnetically vectored and rf-heated plasmas for space propulsion (F. R. Chang-Diaz, et al.\rm, Bull. Am. Phys. Soc., 41, 1541 (1996)) is being investigated experimentally on an asymmetric magnetic mirror device at the Advanced Space Propulsion Laboratory (ASPL), Johnson Space Center, NASA. Analysis of the antenna interaction with and the wave propagation through the dense plasma propulsion system is being studied at ORNL(Oak Ridge National Laboratory, managed by Lockheed Martin Energy Research Corp. for the U.S. Department of Energy under contract number DE-AC05-96OR22464.), using antenna design codes developed for ICH systems and mirror codes developed for the EBT experiment at ORNL. The present modeling effort is directed toward the ASPL experimental device. Antenna optimization and performance, as well as the design considerations for space-qualified rf components and systems (minimizing weight while maximizing reliability) will be presented.

[pThpM2.05] Single Particle Dynamics in a Variable Specific Impulse Magnetoplasma Rocket

A. Ilin ((Lockheed Martin Space Mission Systems amp; Services)), F. R. Chang-Diaz, J. P. Squire ((ASPL/JSC/NASA))

The behavior of single charged particles in a Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is examined. Of particular importance is the effect of a magnetic nozzle in enhancing the axial momentum of the exhaust. Also, different geometries and rocket asymmetries are considered. The magnetic configuration is modeled with an adaptable mesh which increases accuracy without compromising the speed of the simulation. The single particle trajectories are integrated with a finite difference approach which can quickly solve for systems of thousands of particles in a reasonable time (1-2 hours) and without the need for a powerful supercomputer. The magnetic model is also used to examine the possibility for magnetic shielding of human spacecraft, equipped with VASIMR propulsion systems, against some forms of solar radiation.