An Investigation of the Composition of a Hydrogen Plasma using Magnetoacoustic Oscillations

Brennan, M.; Jessup, B.L.; Jones, Ian Rees

doi:10.1071/ph780477

Cited by 7 publications

(8 citation statements)

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“…The experiment was carried out in a magnetized, current-carrying plasma which was generated in a cylindrical discharge tube of 3 m length and 5-2 cm inner radius (the Flinders Plasma Source 2). A schematic diagram of the experimental apparatus can be found in the paper by Brennan et al (1978). The experiment reported here was conducted in a hydrogen plasma with an initial filling pressure of 75mtorr and axial magnetic field of 2kG.…”

Section: Experimental Methods 21 Plasma Generation and Propertiesmentioning

confidence: 99%

“…The centre of the excitation solenoid was located 70 cm from the electrode which, at t = 125/is, acted as the cathode. Details of the excitation and detection of the oscillations are given by Brennan et al (1978). To account for any loading of the solenoid by the plasma, the oscillating axial magnetic field at the plasma boundary was continuously monitored using a small magnetic probe.…”

Section: Excitation and Detection Of The Magneto-acoustic Oscillationsmentioning

confidence: 99%

“…(i) The plasma consists of ions, electrons and neutral atoms. The presence of diatomic molecules is neglected since a previous investigation of an afterglow hydrogen plasma with similar equilibrium parameters (Brennan et al 1978) has shown that molecules couple into the oscillations only very weakly. Negligible error therefore results if the oscillation fields are calculated neglecting the molecular species.…”

Section: Analysis Of the Experimental Datamentioning

confidence: 99%

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Magneto-acoustic oscillations as a plasma diagnostic technique for a current-carrying plasma column

1982

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Magneto-acoustic oscillations were excited in a non-uniform, current-carrying plasma column. Measurements of the oscillating axial magnetic flux at a number of excitation frequencies were used to determine the equilibrium plasma properties. In agreement with previous theoretical studies, the radial profile of the plasma density is shown to be accurately determined, while it is not possible to obtain detailed information on the radial profile of the equilibrium magnetic field.

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Section: Experimental Methods 21 Plasma Generation and Propertiesmentioning

confidence: 99%

Section: Excitation and Detection Of The Magneto-acoustic Oscillationsmentioning

confidence: 99%

Section: Analysis Of the Experimental Datamentioning

confidence: 99%

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Magneto-acoustic oscillations as a plasma diagnostic technique for a current-carrying plasma column

1982

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“…No experiments have been attempted for measuring the field in this way. The inverse problem (measuring B and determining the plasma pressure from the wave propagation) is much more seu.ntive [23].…”

Section: Magneto-acoustic Wave Propagationmentioning

confidence: 99%

Far-infrared polarimetry/interferometry for poloidal magnetic field measurement on ZT-40M

Erickson¹,

Forman²,

Jahoda³

1986

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The measurement of internal magnetic field profiles may be a very important step in the understanding of magnetic confinement physics issues. The measurement of plasma-induced Faraday rotation is one of the more promising internal magnetic field diagnostics, This thesis describes the development of a heterodyne polarimeter/interferometer for internal poloidal magnetic field measurement on ZT-40M. Heterodyne techniques were employed because of the insensitivity to spurious signal amplitude changes that cause errors in other methods. I am grateful to the ZT-40M program management for the contribution of machine access (as poor as it was) and funding, and for their patience during the diagnostic development. I would also like to thank the ZT-40M team for their interest, and for supplying some of the data that is presented in this thesis. I appreciate the friendship and support of the people I have come to know at Los Alamos. Finally, I would like to thank my wife, Laura, for typing the text of this thesis, and Dr. Cris W. Barnes for his help in the preparation of this document. Ill 4.11 Baseline with Four-Signal Technique 112 4.12 Heterodyne Polarimeter on ZT-40M 116 4.13 ZT-40M Interferometer 4.14 Simultaneous Configuration 119 4.15 Revised Simultaneous Configuration 122 4.16 Two-Chord Simultaneous Configuration 123 4.17 Preamplifier Circuit for GaAs Photoconductor 124 4.18 Method for Calculating Carrier-Signal Phase 128 5.1 Polarimetric Measurements Indicating Sensitivity Problems 134 5.2 Theoretical Beam Profiles for Geometry of ZT-40M 139 5.3 Setup for Beam Propagation Measurements 140 5.4 Measured Intensity Profiles for Geometry of ZT-40M 141 5.5 Crossed Polarizer Test Setup 142 5.6 Polarization Azimuth Rotation for Bare Metal, Quartz, and Threaded Tubulations 144 5.7 Reflectivities and Phase Difference for s and p Polarizations for Grazing Angles of Incidence 146 5.8 Polarization Rotation vs. Incident Azimuth 5.9 Quartz Inserts after Removal from ZT-40M 5.10 Profile of Metallic Deposition on Quartz 5.11 Polarimetric Phase for ZT-40M Discharges with Bare Tubulations, Bypassing Torus, and with Threaded Inserts 6.1 Interferometric Measurement with Two-Signal Technique 6.2 Example of Interferometric Measurement in Simultaneous Configuration 6.3 Central-and Edge-chord-averajred Densities 6.4 Examples of Density Sawtooth Oscillations 6.5 Density of Ramped (70 kA to 170 kA) Discharge Compared to Standard 170 kA Discharge 165 6.6 Carrier Signal Measured by the Polarimeter 166 6.7 Toroidal Current and Faraday Rotation for a Design-Mode Discharge 168 7 List of Tables 1.1 Relative Merits of Measurement Techniques 4.1 Laser Gases 6.1 Calculated Faraday Rotation Levels for Various Profiles

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“…Forced magnetoacoustic oscillations have been recently studied because of their application to plasma supplementary heating (Hoegger etal. 1971;Kapitza & Pitaevskii 1975;Jacobson et al 1976) and to diagnostic analysis (Frommelt & Jones 1975;Vaucher, Vaclavik & Schneider 1975;Brennan, Jessup & Jones 1977, 1978. While most theoretical work to date has been confined to currentless plasmas, magnetoacoustic oscillations in a current carrying plasma column have been investigated by Vaclavik (1971) and Sy (1978).…”

Section: Introductionmentioning

confidence: 99%

Magnetoacoustic oscillations in a finite-beta current carrying plasma column

Sawley

1979

J. Plasma Phys.

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Forced magnetoacoustic oscillations in a fully ionized, non-uniform, current carrying plasma column of finite beta are treated theoretically. The results of numerical calculations are given for the specific case of diffuse pinch equilibrium configurations. It is found that, for these configurations, the amplitude of the axial component of the oscillating magnetic field is enhanced and the frequency at which magnetoacoustic resonance occurs is raised. It is also found that the presence of an equilibrium axial current produces a substantial azimuthal component, in addition to the axial component, of the oscillating magnetic field.

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An Investigation of the Composition of a Hydrogen Plasma using Magnetoacoustic Oscillations

Cited by 7 publications

References 0 publications

Magneto-acoustic oscillations as a plasma diagnostic technique for a current-carrying plasma column

Magneto-acoustic oscillations as a plasma diagnostic technique for a current-carrying plasma column

Far-infrared polarimetry/interferometry for poloidal magnetic field measurement on ZT-40M

Magnetoacoustic oscillations in a finite-beta current carrying plasma column

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