Resonant ion heating in a helicon plasma

Kline, J. L.; Scime, Earl; Balkey, M. M.; Boivin, Robert; Keiter, Paul

doi:10.33915/etd.920

Cited by 2 publications

(2 citation statements)

References 14 publications

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“…An external antenna consisting of two spools of wire in the Helmholtz coil configuration, placed on opposite sides of the outside wall of the vessel, with their axis perpendicular to the magnetic field were initially used but did not excite electrostatic waves. The hope was that electromagnetic waves from this external antenna could be converted into electrostatic waves by the plasma [27,28]. We were able to launch an electrostatic wave with an antenna placed inside the vacuum chamber, and consisting of two flat metal plates.…”

Section: Beating Waves Antennamentioning

confidence: 99%

Excitation and Propagation of Electrostatic Ion Cyclotron Waves in rf-Sustained Plasmas of Interest to Propulsion Research

Spektor

Choueiri

2004

40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit

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Excitation and propagation of Electrostatic Ion Cyclotron (EIC) waves in an rf-sustained argon plasma are reported along with measurement of dispersion relation. Such waves can be used to energize the plasmas of a number of promising propulsion concepts. The waves are excited by an antenna consisting of two parallel metal plates inserted at the edge of a plasma column with their surface normal perpendicular to magnetic field. The plates can be driven in or out of phase. The in-phase configuration couples better to plasma. It is shown that EIC waves launched at frequencies between ω ci and 10ω ci propagate with little damping at an angle between 82 • and 86 • with respect to the magnetic field. The amplitude of the excited waves can be optimized by properly matching the impedance of the driving circuit to the plasma and choosing the right plasma conditions. The dispersion relation was measured using a phase-delay technique and was found to be in good agreement with the theoretical EIC dispersion relation over a wide range of frequencies.

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Section: Beating Waves Antennamentioning

confidence: 99%

Excitation and Propagation of Electrostatic Ion Cyclotron Waves in rf-Sustained Plasmas of Interest to Propulsion Research

Spektor

Choueiri

2004

40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit

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“…Building on previous resonant ion heating work conducted by John Kline [62] in the HELIX/LEIA system, the first wave-launching antenna design em- Wave-launching was attempted in both helium (driving frequency at 275…”

Section: External Wave-launching Antenna Designmentioning

confidence: 99%

Alfven Wave Propagation in Inhomogeneous Plasmas

Sears¹

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Damping of Alfvén waves is one of the most likely mechanisms for ion heating in the solar corona. Density gradients have significant but poorlyunderstood effects on energy transfer and Alfvén wave propagation in partially ionized plasmas, such as those found in the solar chromosphere. Reflection of Alfvén waves at density and magnetic field gradients can give rise to turbulence which sustains particle heating. [1],[2] The density profile in the Hot hELIcon eXperiment (HELIX) varies strongly with radius, giving access to a wide range of Alfvén dynamics across the plasma column and providing an ideal environment to observe Alfvén wave-driven particle heating. A new internal wave-launching antenna, situated at the edge of the highdensity core and the density-gradient region of HELIX has been used to excite low-frequency waves in argon plasma. The propagation behavior of the launched waves was measured with a small-scale (smaller than the ion gyroradius) magnetic sense coil at multiple radial locations across the plasma column (from the high-density core through the density gradient region). Time-resolved laser induced fluorescence (LIF) and Langmuir probe measurements also yield insight into the plasma response to the perturbation. This dissertation presents cross-spectral and wavelet analysis of low-frequency waves in a helicon plasma with a strong density gradient. Building on the work of Houshmandyar, [3] shear Alfvén waves were launched in a helicon plasma source with a strong density gradient. Alfvén wave turbulence is suggested from phase angle and wavelet analysis of magnetic sense coil probe measurements. The perturbation wavelength derived from phase angle measurements is consistent with predictions from the full Alfvén wave dispersion relation (taking electron Landua damping, electron-ion collisions, and finite frequency effects into account). Time-resolved LIF measurements across the plasma column suggest ion heating where the turbulence is strongest. Timeresolved Langmuir probe measurements show electron heating in response to the launched Alfvén waves. This work is dedicated to the spirit of Shakespeare's sister and every woman who has ever worked to build a room of her own.

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Resonant ion heating in a helicon plasma

Cited by 2 publications

References 14 publications

Excitation and Propagation of Electrostatic Ion Cyclotron Waves in rf-Sustained Plasmas of Interest to Propulsion Research

Excitation and Propagation of Electrostatic Ion Cyclotron Waves in rf-Sustained Plasmas of Interest to Propulsion Research

Alfven Wave Propagation in Inhomogeneous Plasmas

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