Progress in Experimental Research of the Vasimr Engine

Squire, Jared P.; Díaz, Franklin R. Chang; Glover, T. W.; Jacobson, V. T.; Chavers, D. G.; Bengtson, Roger D.; Bering, Edgar A.; Boswell, Rod; Goulding, R. H.; Light, Max

doi:10.13182/fst03-a11963576

Cited by 17 publications

(17 citation statements)

References 8 publications

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“…15 They have also been used for plasma confinement studies, space-plasma simulation experiments, 16 and are of substantial interest as part of the VASIMR thruster engine for Mars space vehicles. [17][18][19] Recent studies of helicon sources have focused on the physics behind their highly efficient ionization and strong wave damping, which is not fully explained by either collisional or Landau damping processes. The significance of the role of a population of fast electrons constituting a nonMaxwellian component of the electron distribution function in the helicon ionization process is a central question.…”

Section: Introductionmentioning

confidence: 99%

Optical, wave measurements, and modeling of helicon plasmas for a wide range of magnetic fields

et al. 2004

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Helicon waves are excited in a plasma wave facility by a half-turn double-helix antenna operating at 13.56 MHz for static magnetic fields ranging from 200 to 1000 G. A non-perturbing optical probe located outside the Pyrex™ plasma chamber is used to observe 443 nm Ar II emission that is spatially and temporally correlated with the helicon wave. The Ar II emission is measured along with wave magnetic and Langmuir probe density measurements at various axial and radial positions. 105 GHz interferometry is used to verify the bulk temperature corrected Langmuir probe measurements. The measured peak Ar II emission phase velocity is compared to the measured wave magnetic field phase velocity and code predicted wave phase velocity for the transition and blue mode regimes. Very different properties of the optical emission peak phase and wave characteristics for the transition and helicon modes of operation are observed. Comparison of the experimental results with the ANTENAII code ͓Y. Mouzouris and J. E. Scharer, IEEE Trans. Plasma Sci. 24, 152 ͑1996͔͒ is carried out for the wave field measurements for the two regimes of operation.

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Section: Introductionmentioning

confidence: 99%

Optical, wave measurements, and modeling of helicon plasmas for a wide range of magnetic fields

et al. 2004

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“…4. The data used here were part of a series of experiments on diffusion and recombination in the plasma conducted over a period of , four days, and were collected at an axial position at the exit of the confinement tube [6]. The ion-cyclotron resonance heating (ICRH) antenna, normally installed just downstream of this position, was removed for these experiments (it is not shown in the figure).…”

Section: Experimental Plasmasmentioning

confidence: 99%

“…The high-density plasma is the core of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) propulsion testbed and is generated in a long-pulse mode (a few sec.) [6]. The low-density device is a spherical Inertial Electrostatic Confinement (IEC) chamber operating in a sustained discharge mode [7].…”

Section: Introductionmentioning

confidence: 99%

Instrument reflections and scene amplitude modulation in a polychromatic microwave quadrature interferometer

Dobson

Jones

Chavers

2004

Review of Scientific Instruments

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A polychromatic microwave quadrature interferometer has been characterized using several laboratory plasmas. Reflections between the transmitter and the receiver have been observed, and the effects of including reflection terms in the data reduction equation have been examined. An error analysis which includes the reflections, modulation of the scene beam amplitude by the plasma, and simultaneous measurements at two frequencies has been applied to the empirical database, and the results are summarized. For reflection amplitudes around 1096, the reflection terms were found to reduce the calculated error bars for electron density measurements by about a factor of 2. The impact of amplitude modulation is also quantified. In the complete analysis, the mean error bar for highdensity measurements is 7.596, and the mean phase shift error for low-density measurements is 1.2".. PACS no.'s/OCIS codes, etc analogue I. Introduction.

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“…The thruster experiment variable specific impulse magnetoplasma rocket (VASIMR), as given in Ref. 1, is aimed at this goal. Basically, it can be regarded as in the class of magnetoplasma thrusters, with the plasma being created by a high density helicon discharge operating near the lower-hybrid frequency (typically 500-1500 G) followed by an ion cyclotron heating cell (around 5000 G) and finally a magnetic expansion which is designed to accelerate the plasma and convert the perpendicular ion energy into parallel ion energy.…”

Section: Introductionmentioning

confidence: 99%

“…For this instability to occur, the rf pump helicon wave 0 parametrically drives a second lower-frequency "daughter" helicon wave 1 , and a lower-frequency "idler" wave 2 . For the present experiment, this lower frequency wave has a frequency at least five times higher than previously reported, as will be discussed below.…”

Section: Introductionmentioning

confidence: 99%

Experimental evidence of parametric decay processes in the variable specific impulse magnetoplasma rocket (VASIMR) helicon plasma source

et al. 2004

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Decay waves have been observed in the megahertz range in the helium plasma generated by the variable specific impulse magnetoplasma rocket magnetoplasma thruster. They are measured using one of the tips of a triple probe connected to a 50 Ω input of a spectrum analyzer via a dc block (a small capacitor). The maximum amplitude of all waves is in the center of the plasma and does not appear correlated to the radial electron density or temperature profiles. The waves seem to be generated close to the helicon antenna that was 91 cm “upstream” from the measuring Langmuir probe. A possible explanation is parametric decay of the large amplitude helicon wave that also generates the plasma.

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Progress in Experimental Research of the Vasimr Engine

Cited by 17 publications

References 8 publications

Optical, wave measurements, and modeling of helicon plasmas for a wide range of magnetic fields

Optical, wave measurements, and modeling of helicon plasmas for a wide range of magnetic fields

Instrument reflections and scene amplitude modulation in a polychromatic microwave quadrature interferometer

Experimental evidence of parametric decay processes in the variable specific impulse magnetoplasma rocket (VASIMR) helicon plasma source

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