Plasma characteristics of a high power helicon discharge

Ziemba, Timothy; Euripides, P.; Slough, John; Winglee, R. M.; Giersch, Louis; Carscadden, John; Schnackenberg, T; Isley, S

doi:10.1088/0963-0252/15/3/030

Cited by 33 publications

(19 citation statements)

References 23 publications

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“…30 The relatively low power High-Power Helicon (HPH) [31][32][33] thruster developed by the University of Washington and MSNW LLC was used as a plasma source for testing the pendulum against the VF-3 thrust stand. The lower power level ensured that the electromagnetic effects on the metal stand and the chamber walls in VF-3 were minimized while providing a similar platform to the high-powered ELF thruster.…”

Section: Ballistic Pendulummentioning

confidence: 99%

The electrodeless Lorentz force (ELF) thruster experimental facility

Weber

Slough

Kirtley

2012

Review of Scientific Instruments

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An innovative facility for testing high-power, pulsed plasmoid thrusters has been constructed to develop the electrodeless Lorentz force (ELF) thruster concept. It is equipped with a suite of diagnostics optimized to study the physical processes taking place within ELF and evaluate its propulsive utility including magnetic field, neutral gas, and plasma flux diagnostics, a method to determine energy flow into the plasma from the pulsed power systems, and a new type of ballistic pendulum, which enables thrust to be measured without the need for installing the entire propulsion system on a thrust stand. Variable magnetic fields allow controlled studies of plume expansion in a small-scale experiment and dielectric chamber walls reduce electromagnetic influences on plasma behavior and thruster operation. The unique capabilities of this facility enable novel concept development to take place at greatly reduced cost and increased accessibility compared to testing at large user-facilities.

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Section: Ballistic Pendulummentioning

confidence: 99%

The electrodeless Lorentz force (ELF) thruster experimental facility

Weber

Slough

Kirtley

2012

Review of Scientific Instruments

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“…The helicon section itself has been studied at the Oak Ridge National Laboratory 22 with deuterium in a 5-cm diam tube. Supporting experiments on a highpower helicon discharge in argon, also with an inner diameter of order 5 cm, were done at the University of Washington 18,23 .…”

Section: Introductionmentioning

confidence: 99%

Permanent Magnet Helicon Source for Ion Propulsion

Chen

2008

IEEE Trans. Plasma Sci.

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Helicon sources have been proposed by at least two groups for generating ions for space propulsion: the HDLT concept at the Australian National University (ANU), and the VASIMR concept at the Johnson Space Center in Houston. These sources normally require a large electromagnet and power supply to produce the magnetic field. At this stage of research, emphasis has been on the plasma density and ion current that can be produced, but not much on the weight, size, impulse, and gas efficiency of the thruster. This paper concerns the source itself and shows that great savings in size and weight can be obtained by using specially designed permanent magnets (PMs). This PM helicon design, originally developed for plasma processing of large substrates, is extended here for ion thrusters of both the HDLT and VASIMR types. Measured downstream densities are of order 10 12 cm -3 , which should yield much higher ion currents than reported so far. The design principles have been checked experimentally, showing that the predictions of the theory and computations are reliable. The details of two new designs are given here to serve as examples to stimulate further research on the use of such sources as thrusters.

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“…18,19 More recently, high nonthermal ion flows with energies of the order of 30 eV have been observed in association with helicon plasmas produced in laboratory magnetic mirror geometries. 22,23 This latter system uses lower frequency ͑ϳ1 MHz͒ in a few hundred Gauss magnetic field at high densities ͑of the order of 10 12 -10 14 cm −3 ͒ so that the energy density of the plasma is comparable to the energy density of the guide magnetic field, i.e., ␤ ϳ 1. 22,23 This latter system uses lower frequency ͑ϳ1 MHz͒ in a few hundred Gauss magnetic field at high densities ͑of the order of 10 12 -10 14 cm −3 ͒ so that the energy density of the plasma is comparable to the energy density of the guide magnetic field, i.e., ␤ ϳ 1.…”

Section: Introductionmentioning

confidence: 99%

Simulation and laboratory validation of magnetic nozzle effects for the high power helicon thruster

et al. 2007

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The efficiency of a plasma thruster can be improved if the plasma stream can be highly focused, so that there is maximum conversion of thermal energy to the directed energy. Such focusing can be potentially achieved through the use of magnetic nozzles, but this introduces the potential problem of detachment of plasma from the magnetic field lines tied to the nozzles. Simulations and laboratory testing are used to investigate these processes for the high power helicon ͑HPH͒ thruster, which has the capacity of producing a dense ͑10 18 −10 20 m −3 ͒ energetic ͑tens of eV͒ plasma stream which can be both supersonic and super-Alfvénic within a few antenna wavelengths. In its standard configuration, the plasma plume generated by this device has a large opening angle, due to relatively high thermal velocity and rapid divergence of the magnetic field. With the addition of a magnetic nozzle system, the plasma can be directed/collimated close to the pole of the nozzle system causing an increase in the axial velocity of the plasma, as well as an increase in the Alfvén Mach number. As such the magnetic field of the nozzle is insufficient to pull the plasma back to the spacecraft, i.e., plasma attachment is not a problem for the system. Laboratory results show that the specific impulse ͑Isp͒ of the system can be increased by ϳ30% by the addition of the nozzle due to the conversion of thermal energy into directed energy in association with a highly collimated profile. An interesting feature of the system is that self-collimation of the beam is expected to occur during continuous operation through plasma currents induced downstream from the magnetic nozzle. These currents lead to magnetic fields that have a smaller divergence than the original vacuum magnetic field so that the following plasma will be more collimated than the proceeding plasma. This self-focusing can lead to beam propagation over extended distances.

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Plasma characteristics of a high power helicon discharge

Cited by 33 publications

References 23 publications

The electrodeless Lorentz force (ELF) thruster experimental facility

The electrodeless Lorentz force (ELF) thruster experimental facility

Permanent Magnet Helicon Source for Ion Propulsion

Simulation and laboratory validation of magnetic nozzle effects for the high power helicon thruster

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