Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-20T04:55:33.014Z Has data issue: false hasContentIssue false
  • English
  • Français

High ionisation fraction plasmas in a low temperature, multidipole cusp plasma

Published online by Cambridge University Press:  19 June 2018

V. Désangles ,
J. Milhone ,
C. Cooper ,
D. B. Weisberg ,
M. D. Nornberg  and
C. B. Forest Open the ORCID record for C. B. Forest [Opens in a new window]
V. Désangles*
Affiliation:
Univ Lyon, Ens de Lyon, Univ Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, F-69342 Lyon, France
J. Milhone
Affiliation:
Department of Physics, University of Wisconsin, Madison, WI 53706, USA
C. Cooper
Affiliation:
Department of Physics, University of Wisconsin, Madison, WI 53706, USA
D. B. Weisberg
Affiliation:
Department of Physics, University of Wisconsin, Madison, WI 53706, USA
M. D. Nornberg
Affiliation:
Department of Physics, University of Wisconsin, Madison, WI 53706, USA
C. B. Forest
Affiliation:
Department of Physics, University of Wisconsin, Madison, WI 53706, USA
*
†Email address for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The depletion of neutral helium atoms has been studied in an unmagnetised spherical plasma created by DC discharge in a multidipole confinement field. Knowing the neutral density profile is critical to predicting the equilibrium flow of such plasmas. A model of the emissivity due to electron-impact excitation of neutral atoms in the plasma has been derived and used to fit radiance measurements of several neutral transitions to extract the radial profile of neutral density for plasmas of varying temperature and density. We report a depletion of the core neutral density varying between negligible levels to 80 % of the edge neutral density depending on the input power and fuelling. The corresponding ionisation fraction varies between 30–80 % in the plasma core. A simple neutral diffusion model is sufficient to describe the shape of neutral density profile implied by the radiance measurements. We have used the measurements to include a drag force due to neutral charge-exchange collisions in simulations of driven plasma flow. The simulation predicts a better fit to Mach probe flow measurements when this neutral drag is accounted for. This work shows that accounting for a realistic neutral profile is important to predict the plasma flow geometry and its magnetohydrodynamics (MHD) stability.

Keywords

plasma diagnosticsplasma dynamicsplasma flows
Type
Research Article
Information
Journal of Plasma Physics , Volume 84 , Issue 3 , June 2018 , 905840312
Copyright
© Cambridge University Press 2018 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Aanesland, A., Liard, L., Leray, G., Jolly, J. & Chabert, P. 2007 Direct measurements of neutral density depletion by two-photon absorption laser-induced fluorescence spectroscopy. Appl. Phys. Lett. 91 (12), 121502.Google Scholar
Allen, J. E. & Thonemann, P. C. 1954 Current limitation in the low-pressure mercury arc. Proc. Phys. Soc. Lond. 67 (10), 768–774.Google Scholar
Amnon, F. 2008 Neutral depeletion in a collisionless plasma. IEEE Trans. Plasma Sci. 36 (2), 403–413.Google Scholar
Benilov, M. S. 1999 Analysis of ionization non-equilibrium in the near-cathode region of atmospheric-pressure arcs. J. Phys. D: Appl. Phys. 32 (3), 257–262.Google Scholar
Benilov, M. S.2005 Departamento de Física, Universidade da Madeira, 9000 Funchal, Portugal Ionization length in a plasma of arbitrary ionization degree. 1–2; http://www.arc_cathode.uma.pt.Google Scholar
Boffard, J. B., Jung, R. O., Lin, C. C. & Wendt, A. E. 2009 Measurement of metastable and resonance level densities in rare-gas plasmas by optical emission spectroscopy. Plasma Sources Sci. Technol. 18 (3), 035017.Google Scholar
Boivin, R. F., Kline, J. L. & Scime, E. E. 2001 Electron temperature measurement by a helium line intensity ratio method in helicon plasmas. Phys. Plasmas 8 (12), 5303–5314.CrossRefGoogle Scholar
Boivin, R. F., Loch, S. D., Ballance, C. P., Branscomb, D. & Pindzola, M. S. 2007 Line ratio diagnostics in helium and helium seeded argon plasmas. Plasma Sources Sci. Technol. 16 (3), 470–479.Google Scholar
Collins, C., Katz, N., Wallace, J., Jara-Almonte, J., Reese, I., Zweibel, E. & Forest, C. B. 2012 Stirring unmagnetized plasma. Phys. Rev. Lett. 108 (11), 115001.Google Scholar
Cook, T. B., King, P. W., Roberto, J. B., Stewart, K. A. & Yokoyama, K. E. 1984 Time-resolved erosion measurements using laser-induced fluorescence at a reference limiter in ISX-B. J. Nucl. Mater. 129 (1984), 253–256.Google Scholar
Cooper, C. M., Wallace, J., Brookhart, M., Clark, M., Collins, C., Ding, W. X., Flanagan, K., Khalzov, I., Li, Y., Milhone, J. et al. 2014 The Madison plasma dynamo experiment: a facility for studying laboratory plasma astrophysics. Phys. Plasmas 21 (1), 013505.Google Scholar
Cooper, C. M., Weisberg, D. B., Khalzov, I., Milhone, J., Flanagan, K., Peterson, E., Wahl, C. & Forest, C. B. 2016 Direct measurement of the plasma loss width in an optimized, high ionization fraction, magnetic multi-dipole ring cusp. Phys. Plasmas 23, 102505.Google Scholar
Forest, C. B., Flanagan, K., Brookhart, M., Clark, M., Cooper, C. M., Desangles, V., Egedal, J., Endrizzi, D., Khalzov, I. V., Li, H. et al. 2015 The Wisconsin plasma astrophysics laboratory. J. Plasma Phys. 81 (5), 345810501; arXiv:1506.07195v2.Google Scholar
Fruchtman, A., Makrinich, G., Raimbault, J. L., Liard, L., Rax, J. M. & Chabert, P. 2008 Neutral depletion versus repletion due to ionization. Phys. Plasmas 15 (5), 057102.Google Scholar
Gekelman, W., Pribyl, P., Lucky, Z., Drandell, M., Leneman, D., Maggs, J., Vincena, S., Van Compernolle, B., Tripathi, S. K. P., Morales, G. et al. 2016 The upgraded large plasma device, a machine for studying frontier basic plasma physics. Rev. Sci. Instrum. 87 (2), 1–19.CrossRefGoogle ScholarPubMed
Gilland, J., Breun, R. & Hershkowitz, N. 1999 Neutral pumping in a helicon discharge. Plasma Sources Sci. Technol. 7 (3), 416–422.Google Scholar
Gilmore, M., Lynn, A. G., Desjardins, T. R., Zhang, Y., Watts, C., Hsu, S. C., Betts, S., Kelly, R. & Schamiloglu, E. 2015 The HelCat basic plasma science device. J. Plasma Phys. 81 (1), 345810104.Google Scholar
Holland, C., Yu, J. H., James, A., Nishijima, D., Shimada, M., Taheri, N. & Tynan, G. R. 2006 Observation of turbulent-driven shear flow in a cylindrical laboratory plasma device. Phys. Rev. Lett. 96 (19), 195002.Google Scholar
Huba, J. D. 2013 NRL Plasma Formulary. Naval Research Laboratory.Google Scholar
Muñoz Burgos, J. M., Schmitz, O., Loch, S. D. & Ballance, C. P. 2012 Hybrid time dependent/independent solution for the He I line ratio temperature and density diagnostic for a thermal helium beam with applications in the scrape-off layeredge regions in tokamaks. Phys. Plasmas 19 (1), 012501.Google Scholar
Janev, R. K., Langer, W. D., Post, D. E. & Evans, K. 1987 Elementary Processes in Hydrogen–Helium Plasmas, Springer Series on Atomic, Optical, and Plasma Physics, vol. 4, pp. 1–326. Springer, Berlin Heidelberg.Google Scholar
Keesee, A. M. & Scime, E. E. 2006 Neutral argon density profile determination by comparison of spectroscopic measurements and a collisional-radiative model (invited). Rev. Sci. Instrum. 77 (10), 10F304.Google Scholar
Khalzov, I. V., Brown, B. P., Cooper, C. M., Weisberg, D. B. & Forest, C. B. 2012 Optimized boundary driven flows for dynamos in a sphere. Phys. Plasmas 19 (11), 1–26.Google Scholar
Khalzov, I. V., Cooper, C. M. & Forest, C. B. 2013 Fast dynamos in spherical boundary-driven flows. Phys. Rev. Lett. 111 (12), 125001.Google Scholar
Lieberman, M. A. & Lichtenberg, A. J. 2005 Principles of Plasma Discharges and Materials Processing. pp. 1–800. Wiley.Google Scholar
MacWhirter, R. W. P. 1965 Plasma Diagnostic Techniques. p. 201. Academic Press, New York.Google Scholar
Plihon, N., Bousselin, G., Palermo, F., Morales, J., Bos, W. J. T., Godeferd, F., Bourgoin, M., Pinton, J. F., Moulin, M. & Aanesland, A. 2014 Flow dynamics and magnetic induction in the von-Karman plasma experiment. J. Plasma Phys. 81 (1), 1–17; arXiv:1409.3139v1.Google Scholar
Sakabe, S. & Izawa, Y. 1991 Cross sections for resonant charge transfer between atoms and their positive ions: collsion velocity ${<}$ 1 a.u. At. Data Nucl. Data Tables 49 (2), 257–314.Google Scholar
Sasaki, S., Takamura, S., Masuzaki, S., Watanabe, S., Kato, T. & Kadota, K. 1996 Helium I line intensity ratios in a plasma for the diagnostics of fusion edge plasmas. Natl Inst. Fusion Sci. 67 (10), 3521–3529.Google Scholar
Scime, E. E., Keiter, P. A., Balkey, M. M., Kline, J. L., Sun, X., Keesee, A. M., Hardin, R. A., Biloiu, I. A., Houshmandyar, S., Chakraborty Thakur, S. et al. 2015 The hot hELicon eXperiment (HELIX) and the large experiment on instabilities and anisotropy (LEIA). J. Plasma Phys. 81 (1), 345810103.Google Scholar
Weisberg, D. B., Peterson, E., Milhone, J., Endrizzi, D., Cooper, C., Désangles, V., Khalzov, I., Siller, R. & Forest, C. B. 2017 Driving large magnetic Reynolds number flow in highly ionized, unmagnetized plasmas. Phys. Plasmas 24 (5), 056502.Google Scholar
Yun, S., Taylor, K. & Tynan, G. R. 2000 Measurement of radial neutral pressure and plasma density profiles in various plasma conditions in large-area high-density plasma sources. Phys. Plasmas 7 (8), 3448–3456.Google Scholar