In some cases we have electronic versions of the papers, and in other cases just the reference to the item. These papers are from refereed publications, conferences, or lab reports.
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FRC Collaboration Papers:
Diagnostic Papers:
G. A. Wurden, B. J. Peterson, Shigeru Sudo. Design of an imaging bolometer system for the large helical device. Review of Scientific Instruments, 68, No. 1, pg. 766-769 (1997). Keywords: stellarator, LHD, pinhole camera, segmented matrix, IR camera, multi-channel imager, plasma radiation and particles.
G. A. Wurden. "A radiation-hard, steady-state, digital imaging bolometer system". in Fusion Engineering and Design, Vol 34-35, 301-305 (1997). LA-UR-95-4339. Keywords: imaging bolometer, IR camera, fusion plasma, Toki Conference proceedings.
G. A. Wurden. " A rad-hard, steady-state, digital imaging bolometer system for ITER ", In Diagnostics for Experimental Thermonuclear Fusion Reactors, edited by P. E. Stott, et. al., Plenum Press, NY, (1996). Pg. 603-606. LA-UR-95-2993. Keywords: radiation-hard, IR camera, segmented matrix, plasma radiation detector.
S. Davis, D. Barnes, T. Casper, R. Fonck, T. Fredian, T. Gibney, M. Greenwald, P. Henliine, K. Keith, B. McHarg, W. Meyer, J. Moller, P. Roney, J. Stillerman, and G. Wurden "Experiences with Remote Collaborations in Fusion Research" (html), Symposium on Fusion Engineering (SOFE) Conference, San Diego, CA. Oct. 5-10, 1997. LA-UR-97-4313. Keywords: remote control, videoconferencing, virtual control room, TFTR, JT-60U, Alcator, DIII-D.
Cris W. Barnes, Hau H. Duong, D. L. Jassby, L. C. Johnson, A. R. Larson, G. LeMunyan, M. J. Loughlin, A. L. Roquemore, S. Sesnic, J. D. Strachan, S. von Goeler, and G. A. Wurden. "DT Neutron Measurements and Experience on TFTR". In Diagnostics for Experimental Thermonuclear Fusion Reactors, edited by P. E. Stott, et. al., Plenum Press, NY, (1996). Pg. 379-383. LA-UR-95-2655. Keywords: Tokamak, TFTR, neutron calibration, deuterium-tritium plasmas.
Cris W. Barnes, S. D. Scott, et. al., "Confinement analysis in low-confinement mode of hydrogen isotope experiments on the Tokamak Fusion Test Reactor". Physics of Plasmas, Vol 3, No. 12, pg. 4521-4535 (1996). Keywords: Tokamak, TFTR, isotope effect, confinement scaling, hydrogen, deuterium, ohmic heating, neutral beam heating.
Cris W. Barnes and A. R. Larsen, "Calculations of Neutron Activation Response for the Tokamak Fusion Test Reactor, and Absolute Calibrations of Neutron Yield", Fusion Technology 30, pg. 63--72 (1996). Keywords: absolute neutron calibration, MCNP code, TFTR, tokamak.
C. W. Barnes, et. al.Design Considerations for Neutron Activation and Neutron Source Strength Monitors for ITER, ITER Diagnostics Workshop, Varenna, Italy, Sept. 4-12, 1997. LA-UR-97-3587. Keywords: neutrons, ITER.
Cris W. Barnes and A. L. Roquemore, Neutron Source Strength Monitors for ITER", A paper for Review of Scientific Instruments for the 11th Topical Conference on High Temperature Plasma Diagnostics (LA-UR-96-1651). Rev. Sci. Instrum. 68 No. 1, (1997) 573--576. Keywords: ITER neutron diagnostics, uranium fission chambers.
Cris W. Barnes, Michael Loughlin, and Takeo Nishitani. Neutron Activation for ITER " A paper for Review of Scientific Instruments for the 11th Topical Conference on High Temperature Plasma Diagnostics (LA-UR-96-1608). Rev. Sci. Instrum. 68 No. 1, (1997) 577--580. Keywords: ITER neutron diagnostics, absolute calibration, activation systems.
K. M. McGuire, C. W. Barnes, S. Batha, et. al. "Physics of High Performance Deuterium-Tritium Plasmas in TFTR", 16th IAEA Fusion Energy Conference, Montreal, Canada, Oct. 7-11, 1996. IAEA-F1-CN-64/01-2. Keywords: Tokamak, TFTR, deuterium-tritium operation, confinement, stability, transport.
T. Nishitani, M. Hoek, H. Harano, M. Isobe, K. Tobita, Y. Kusama, G. A. Wurden, and R. E. Chrien. "Triton burn-up study in JT-60U". Plasma Physics and Controlled Fusion, Vol 38, pg. 355-364, (1996). LA-UR-95-3156. Keywords: Tokamak, JT-60U, scintillating fiber neutron detectors, 14 MeV neutrons, triton diffusivity, time-resolved measurements, toroidal ripple.
A. J. Allen, J. L. Terry, D. Garnier, J. A. Stillerman, and G. A. Wurden. The high resolution video capture system on the alcator C-Mod tokamk. Review of Scientific Instruments, 68, No. 1, pg. 947-950 (1997). Keywords: tokamak, Alcator C-Mod, video capture, frame grabber, fast fluctuations, plasma radiation.
Glen A. Wurden and D. O. Whiteson. "High-Speed Plasma Imaging: A Lightning Bolt" IEEE Transactions on Plasma Science, 24(1), pg. 83-84 (1996) Keywords: Lightning, gated intensified video camera, stepped leader.
G. A. Wurden, A. J. Wurden, and I. M. Gladstone. "Plasma Tails: Comets Hyakutake and Hale-Bopp", IEEE Transactions on Plasma Science, 27 (1), pg. 142-143 (1999). LA-UR-98-3007. Keywords: plasma tail, dust tail, comet, bluish color, whitish color, photographs.
T. H. Ivers, E. Eisner, A. Garofalo, R. Kombargi, M. E. Mauel, D. Maurer, D. Nadle, G. A. Navratil, M. K. V. Sankar, M. Su, E. Taylor, Q. Xiao, COLUMBIA UNIVERSITY, R. R. Bartsch, W. A. Reass, and G. A. Wurden, LOS ALAMOS NATIONAL LABORATORY. "Observation of wall stabilization and active control of low-n magnetohydrodynamic instabilities in a tokamak". Physics of Plasmas, 3 (5), pg. 1926-1934 (1996). Keywords: Tokamak, HBT-EP, modular saddle coils, active feedback, movable conducting wall, m=2 instability, rotation velocity modulation.
R. J. Maqueda, Cris W. Barnes, S. S. Han, P. A. Staples, and R. S. Wagner. "Proton recoil detector of fusion neutrons using natural diamond". Rev. Sci. Instrum. 68 No. 1, (1997) 624-627. Keywords: neutron detector, energy resolving, diamond, tests at LANSCE.
H. A. Davis, J. C. Olson, W. A. Reass, Cris W. Barnes, and R. R. Bartsch; D. M. Coates, J. W. Hunt, and H. M. Schleinitz; R. H. Lovberg; J. B. Greenly. "Progress toward a microsecond duration, repetitively pulsed, intense-ion beam for active spectroscopic measurements on ITER". Rev. Sci. Instrum. 68 No. 1, (1997) 332-335. Keywords: ITER, beam-plasma systems, ion temperature, charge exchange, plasma diagnostic, high intensity pulsed beam.
W. M. Parsons, E. O. Ballard, R. R. Bartsch, et. al. "The Atlas Project", IEEE Trans. on Plasma Science, Vol 25, No. 2, 205-211 (1997). Keywords: Pulsed power, machine design, LANL, hydrodynamic experiments, high energy density physics.
M. Tuszewski, R. R. White, and G. A. Wurden, "Relaxation oscillations of low-frequency Ar/SF6 inductive plasma discharges" ", Plasma Sources Sci. Technol. 12 396-402 (2003). Keywords: plasma source instability, two-species, relaxation oscillation, high-speed video, langmuir probe.
I. Furno, T. Intrator, E. Torbert, C. Carey, M. D. Cash, J. K. Campbell, Fienup, W. J., C. A. Werely, G. A. Wurden, G. Fiksel, "Reconnection scaling experiment: A new device for three-dimensional magnetic reconnection studies" ", Rev. Sci. Instrum. 74(4) 2324 (2003). Keywords: magnetic reconnection, plasma gun, linear machine.
The favorable properties of the ST arise from its very small aspect ratio (A less than equal to 1.5). To minimize the aspect ratio, elimination of the central solenoid is a consideration for future ST designs. Coaxial Helicity Injection (CHI) on NSTX produced 130kA of toroidal current without the use of the central solenoid. Results demonstrate that there are no fundamental obstacles to applying CHI in a large plasma device. The July to September CHI campaign is expected to produce toroidal currents in excess of 200kA using the full CHI injector current capability of 50kA at 1kV that is now available. Improvements to the MFIT and EFIT computer codes will be used in efforts to detect the generation of closed flux in an optimized plasma configuration. * Work supported by U.S. DOE contract DE-AC02-76CH03073, DE-FG03-99ER54519
Experiments have been conducted to examine the operational domain of NSTX and the equilibrium response to plasma phenomena. Limiter, double-null and single-null diverted configurations have been created. The equilibria have been reconstructed using an automated version of the EFIT code and cover the range 1.6 < \kappa < 2.3, 0.25 < \delta < 0.45, 0.3 < l_i < 1.6 at B_t < 0.3 T, and an aspect ratio A = 1.3, with peak I_p < 1 MA. Pulse duration at nominally constant I_p is typically 4 - 5 energy confinement times. Induced currents in the vacuum vessel wall and conducting plate structure are significant (up to 0.3 MA) and must be included in the analysis. Ohmic plasma stored energy, W_tot has reached 48 +/- 10 kJ (\beta_t = 8.7 percent), with peak energy confinement time of 25 ms (18 ms at peak W_tot). Equilibrium dynamics during startup, internal reconnection events, vertical instabilities, and other gross plasma phenomena are reproduced.
Lawrence Livermore National Laboratory, Livermore, CA 94551. Recent SSPX operations have produced plasma discharges sustained for 2msec with I_P\simeq 600kA, B_pol\simeq 0.25 T, and n\simeq2e20m^-3. Shots with good wall conditioning show clear evidence of impurity ‘burn-through’ and increased magnetic decay time to \simeq1msec indicating higher temperatures. These higher T_e discharges are terminated by a rapid event evidenced by an increase in magnetic field decay-rate and H-alpha emission, and may result from high a \beta instability (also observed in CTX^1). Additionally, the possibility of encountering a \beta--limit during the driven phase will be explored. Direct measurements with a Thomson scattering diagnostic will allow these phenomena to be studied. Initially, a single spatial measurement will give T_e in the core, and ultimately, ten spatial channels will provide temperature and pressure profiles. 1. Wysocki et al Phys. Rev. Lett. V61, No.21, p2457 (1988). This work was performed under the auspices of the USDOE by UCLLNL under contract No. W-7405-Eng-48.
A new method of actively modifying the plasma-wall interaction was tested on the Tokamak Fusion Test Reactor. The use of a laser to introduce a directed lithium aerosol into the discharge scrape-off layer allowed the plasma-wall interaction to be influenced in situ by external means. Significant improvement in energy confinement and neutron production rates as well as a reduction in the plasma Zeff have been documented. The introduction of a metallic aerosol into the plasma edge increased the internal inductance of the plasma column and also resulted in prompt heating of core electrons. Preliminary evidence suggests that the introduction of an aerosol may lead to the formation of an edge transport barrier.
We present the status of the LANL high-density Field Reversed Configuration (FRC). This FRC will be the target plasma for Magnetized Target Fusion (MTF) experiments; heating it by compressing it inside an imploding flux conserver should allow access to fusion conditions.We present our current experimental setup to study the pre-ionization, formation, and translation phases of the FRC. Diagnosing of this plasma is challenging due to the short timescales, high energy densities, high magnetic fields, and restricted access. Our goal is an FRC with n\sim10^17cm^-3, T\sim100-300eV, B\sim5T, and a lifetime of 10-20\mus. According to previous experience, the pre-ionization process is crucial for good FRC formation. We will show initial results of the pre-ionization experiments, which ionize the gas by impressing a rapidly oscillating (\sim300kHz) axial magnetic field over a slower-timescale magnetic bias field of comparable magnitude. This occurs just prior to the theta pinch coil magnetic field reversal. This is a much (10\times) larger field that radially contracts and forms the closed field lines for the FRC. (PDF File of the Poster)
Turbulent filaments in visible light emission have been observed in NSTX with similar characteristics to those seen in TFTR, ASDEX, Alcator C-Mod, DIII-D, and MAST. These filaments were observed by viewing a localized gas puff with a fast-framing, intensified, digital visible camera (i.e., Gas Puff Imaging). The views employed are either in the toroidal vs. poloidal or radial vs. poloidal planes. Initial results in NSTX show that the turbulent filaments are well aligned with the magnetic field (EFIT reconstructions), which can be up to 45^o from the horizontal at the outer midplane of NSTX. The dominant wavelength perpendicular to the magnetic field is \sim7-11 cm, corresponding to a k_\perp\rho_s of \sim0.3 at an assumed T_e=25 eV, and the frequency spectra has a typical broad shape characteristic of edge turbulence extending to about 100 kHz. The characteristic radial scale-length appears to be in the 3-5 cm range. The experimental result will be compared with those from the BOUT turbulence code of LLNL.
[WP1.071] Some Analytical Solutions to Steady-state Axisymmetric Magnetohydrodynamics Equations with Flow
Zhehui Wang, Cris W. Barnes, G. A. Wurden (Los Alamos National Laboratory)High-speed plasma jets and cosmic wind are common phenomena in the universe. In fusion experiments, when a lot of external energies are used to heat the plasma, plasma motion, such as rotation and flow along the magnetic fields, have been observed routinely. These diverse phenomena are believed to be described by the magnetrohydrodynamics (MHD) equations. With assumptions of steady-state and axisymmetry, the MHD equations reduce to the generalized Grad-Shafranov (or Grad-Schluter-Shafranov) (G2S/G2S2) equations with flow. We have solved the G2S/G2S2 under various assumptions. Implication of the solutions to spheromak and magneto-plama-dynamic (MPD) acceleration are discussed.
[MP1.122] Power Coupling of the Rotating Magnetic Field to the Plasma in the Translation, Confinement and Sustainment Experiment
Stephen Tobin, Louis Schrank (Affiliation), Glen Wurden (Los Alamos National Laboratory), Bob Brooks, Ed Crawford, Houyang Guo, Alan Hoffman, Dan Lotz, John Slough (Affiliation), George Votroubek (Redmond Plasma Physics Laboratory), Los Alamos National Laboratory Collaboration, Redmond Plasma Physics Laboratory CollaborationExperimental results utilizing the rotating magnetic field (RMF) current drive system at TCS are presented. The procedure at TCS is to form a hot, FRC (RFTP method); translate it to the confinement chamber; then drive a poloidal current in it with a RMF so that the magnetic flux is sustained. The goal is to sustain the flux so that the lifetime of the FRC becomes limited by particle inventory rather that resistive flux losses, as is presently the case. In addition, the RMF can form FRCs from a pre-ionized gas fill. Experiments to date have been conducted with the following properties: RMF field strengths of about 25 G (1 mWb flux), densities of about 0.5x10^19 m^-3, electron temperatures of about 100 eV, and external fields of 150 G. This poster will address the coupling of the RMF power to the plasma, in particular, how this coupling varies with density and RMF properties (field strength, frequency, pulse width and relative phasing).
[NP1.052] Reconnection Scaling Experiment (RSX) – 3D movies of magnetic reconnection in linear geometry at Los Alamos National Laboratory
T. Intrator, C. Sovinec, D. Begay (Los Alamos National Laboratory), S. Calloway (Northern New Mexico Community College), C. Werley (Los Alamos High School), B. Lasley (Norfolk State Univ.)The physics of magnetic reconnection is a major unsolved issue in MagnetoHydroDynamics (MHD) and plays a fundamental role in changing the magnetic field topology for many astrophysical and laboratory plasmas. Magnetic flux annihilates and transforms into plasma kinetic energy beyond the scope of ideal MHD. We are presently building the linear Reconnection Scaling Experiment (RSX) at LANL to access the scaling between collisional and collisionless reconnection regimes. Plasma gun technology developed at the Univ. of Wisconsin generates high density (>10^14cm^-3) high current (J\sim300A/cm^2) ohmically heated (T_e>15eV) channels. As the reconnection region sweeps down a 4 meter plasma column we create 3D movies of magnetic reconnection from many repetitive shots. We will attack problem with the experiment, modeling using 3D fluid (NIMROD) and particle simulations of the reconnection region. This approach represents synergistic collaborations across divisions within the LANL community and has a substantial student participation.
40th Annual Meeting of the Division of Plasma Physics of the American Physical
Society, 1998 (New Orleans). Abstracts:
"Measurement of MTF Target Plasma Temperature Using Filtered Photodiodes", J. M. Taccetti, F. J. Wysocki, G. Idzorek, H. Oona, R. C. Kirkpatrick, I. R. Lindemuth, P. T. Sheehey, F. Y. Thio.
"Divertor surface heating in Alcator C-Mod", R. J. Maqueda, G. A. Wurden (Los Alamos National Laboratory), J. L. Terry (Plasma Science and Fusion Center MIT).
"Field Reversed Configuration Target Design for a Magnetized Target Fusion Experiment", G. A. Wurden, K. F. Schoenberg, R. E. Siemon, M. Tuszewski, F. Wysocki (Los Alamos National Laboratory), R. D. Milroy (U of Washington).
"Magnetized Target Fusion Proof-of-Principle (PoP Proposal)", R..E. Siemon, R.J. Bartlett, R.R. Bartsch, C.A. Ekdahl, R.J. Faehl, J. Finn, R.A. Gerwin, R. Kirkpatrick, I.R. Lindemuth, R.W. Moses, R.E. Reinovsky, K.F. Schoenberg, P.T. Sheehey, J.S. Shlachter, M.G. Tuszewski, G.A. Wurden, F.J. Wysocki (LANL), J. Degnan, G.F. Kiuttu, E.L. Ruden, P. Turchi (AFRL), P. Parks (GA), J.H. Hammer, R. Moir, D. Ryutov (LLNL), Y.C.F. Thio (Massey Univ, New Zealand), R.D. Milroy (U. Washington), L. Green (Westinghouse)
[dMopP3.15] Plasma Rotation Control using Multiple Helicity Saddle Coils in HBT-EP D. Maurer, C. Cates, M.E. Mauel, D. Nadle, G.A. Navratil, E. Taylor, Q. Xiao (Columbia University), S. Paul (Princeton University), W. Reass, G.A. Wurden (LANL)
[gTuaP3.16] Experiment and Modeling of Atmospheric Pressure Arc in Applied Oscillating Magnetic Field Max Karasik, L Roquemore, S.J. Zweben (Princeton Plasma Physics Lab), E. May (UNC Chapel Hill), G.A. Wurden (Los Alamos National Lab)
38th Annual Meeting of the Division of Plasma Physics of the American Physical
Society, 1996 (Denver). Abstracts:
"Fast Imaging Diagnostic on
TFTR", G. A. Wurden, R. J. Maqueda, G. Lemunyan, D. Long, and S. Medley.
"Disruptions and Runaway
Production in TFTR", R. J. Maqueda, G. A. Wurden, E. D. Fredrickson, and Z.
Chang.
"Study of the Lithium
Deposition Profile on the TFTR Inner Bumper Limiter in Discharges with Li-Pellet Injection",
K. W. Hill, D. K. Mansfield, M. G. Bell, B. Davis, H. W. Kugel, S. S. Medley, A. T.
Ramsey, C. H. Skinner, J. D. Strachan, C. E. Bush, J. Hogan, G. A. Wurden, and W. Tighe.
"Recent Results with the
Penning Fusion Experiment (PFX)", T. B. Mitchell, M. M. Schauer, D. C. Barnes.
"Beyond the Brillouin Limit
with the Penning Fusion Experiment (invited talk)", D. C. Barnes.
"Magnetic Feeback
Experiments on MHD Instabilities in HBT-EP", D. Nadle, E. Eisner, A. Garofalo, T.
H. Ivers, R. Kombargi, M. E. Mauel, D. Maurer, G. A. Navratil, A. Sainz, M. K. V. Sankar,
E. Taylor, Q. Xiao, W. A. Reass, G. A. Wurden.
"Overview of HBT-EP
Experimental Program", HBT-EP Group, G. A. Navratil, E. Eisner, A. Garofalo, T.
H. Ivers, R. Kombargi, M. E. Mauel, D. Maurer, D. Nadle, A. Sainz, M. K. V. Sankar, M.
Taylor, Q. Xiao, W. A. Reass, G. A. Wurden.
"Plasma Rotation Control
using Resonant Magnetic Perturbations from Single- and Multiple- Helicity Saddle Coils",
T. H. Ivers, E. A. Eisner, A. Garofalo, R. Kombargi, M. E. Mauel, D. Maurer, D. Nadle, G.
A. Navratil, A. Sainz, M. K. V. Sankar, M. Taylor, Q. Xiao, W. A. Reass, G. A. Wurden.
"Magnetic Feeback
Experiments on MHD Instabilities in HBT-EP", D. Nadle, E. Eisner, A. Garofalo, T.
H. Ivers, R. Kombargi, M. E. Mauel, D. Maurer, G. A. Navratil, A. Sainz, M. K. V. Sankar,
E. Taylor, Q. Xiao, W. A. Reass, G. A. Wurden.
"Analysis of Feedback
Experiments for the Control of Rotating Resistive Modes in HBT-EP", M. K. Vijaya
Sankar, E. Eisner, A. Garofalo, T. H. Ivers, R. Kombargi, M. E. Mauel, D. Maurer, D.
Nadle, G. A. Navratil, A. Sainz, M. K. V. Sankar, E. Taylor, Q. Xiao, W. A. Reass, G. A.
Wurden.
"Plasma Response to Static
and Single-Phase Oscillating Resonant Magnetic Perturbations", D. Maurer, T. H.
Ivers, E. Eisner, A. Garofalo, T. H. Ivers, R. Kombargi, M. E. Mauel, G. A. Navratil, A.
Sainz, M. K. V. Sankar, E. Taylor, Q. Xiao, W. A. Reass, G. A. Wurden.
Last updated:08/22/07