11 Matching Results

Search Results

Advanced search parameters have been applied.

in creator/contributor: "Moller, J."

open access

TMX-U computer system in evolution

Over the past three years, the total TMX-U diagnsotic data base has grown to exceed 10 megabytes from over 1300 channels; roughly triple the originally designed size. This acquisition and processing load has resulted in an experiment repetition rate exceeding 10 minutes per shot using the five original Hewlett-Packard HP-1000 computers with their shared disks. Our new diagnostics tend to be multichannel instruments, which, in our environment, can be more easily managed using local computers. Fo… more

Date: March 4, 1986

Creator: Casper, T. A.; Bell, H.; Brown, M.; Gorvad, M.; Jenkins, S.; Meyer, W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Field and Current Amplification in the SSPX Spheromak

Results are presented from experiments relating to magnetic field generation and current amplification in the SSPX spheromak. The SSPX spheromak plasma is driven by DC coaxial helicity injection using a 2MJ capacitor bank. Peak toroidal plasma currents of up to 0.7MA and peak edge poloidal fields of 0.3T are produced; lower current discharges can be sustained up to 3.5msec. When edge magnetic fluctuations are reduced below 1% by driving the plasma near threshold, it is possible to produce plasm… more

Date: October 8, 2002

Creator: Hill, D. N.; Blumer, R. H.; Cohen, B. I.; Hooper, E. B.; McLean, H. S.; Moller, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Spheromak formation studies in SSPX

We present results from the Sustained Spheromak Physics Experiment (SSPX) at LLNL, which has been built to study energy confinement in spheromak plasmas sustained for up to 2 ms by coaxial DC helicity injection. Peak toroidal currents as high as 600kA have been obtained in the 1m dia. (0.23m minor radius) device using injection currents between 200-400kA; these currents generate edge poloidal fields in the range of 0.2-0.4T. The internal field and current profiles are inferred from edge field m… more

Date: September 29, 2000

Creator: Hill, D. N.; Bulmer, R. H.; Cohen, B. L.; Hooper, E. B.; LoDestro, L. L.; Mattor, N. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Electron Cyclotron Heating and Current Drive for Maintaining Minimum q in Negative Central Shear Discharges

Toroidal plasmas created with negative magnetic shear in the core region offer advantages in terms of MHD stability properties. These plasmas, transiently created in several tokamaks, have exhibited high performance as measured by normalized stored energy and neutron production rates. A critical issue with extending the duration of these plasmas is the need to maintain the off-axis-peaked current distribution required to support the minimum in the safety factor q at large radii. We present equi… more

Date: April 24, 2003

Creator: Casper, T. A.; Kaiser, T. B.; Jong, R. A.; LoDestro, L. L.; Moller, J.; Pearlstein, L. D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Time-resolved Temperature Measurements in SSPX

We seek to measure time-resolved electron temperatures in the SSPX plasma using soft X-rays from free-free Bremsstrahlung radiation. To increase sensitivity to changes in temperature over the range 100-300 eV, we use two photodiode detectors sensitive to different soft X-ray energies. The detectors, one with a Zr/C coating and the other with a Ti/Pd coating, view the plasma along a common line of sight tangential to the magnetic axis of the spheromak, where the electron temperature is a maximum… more

Date: August 14, 2006

Creator: Ludington, A. R.; Hill, D. N.; McLean, H. S.; Moller, J. & Wood, R. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

LLNL superconducting magnets test facility

The FENIX facility at Lawrence Livermore National Laboratory was upgraded and refurbished in 1996-1998 for testing CICC superconducting magnets. The FENIX facility was used for superconducting high current, short sample tests for fusion programs in the late 1980s--early 1990s. The new facility includes a 4-m diameter vacuum vessel, two refrigerators, a 40 kA, 42 V computer controlled power supply, a new switchyard with a dump resistor, a new helium distribution valve box, several sets of power … more

Date: September 16, 1999

Creator: Manahan, R.; Martovetsky, N.; Moller, J. & Zbasnik, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Progress in the SSPX Spheromak

The spheromak, with its simply connected geometry, holds promise as a less expensive fusion reactor. It has reasonably good plasma beta and can be formed and sustained in steady state with a magnetized coaxial plasma gun. The Sustained Spheromak Physics Experiment (SSPX) shown in Fig. 1 was constructed to investigate the key issues of magnetic field generation and energy confinement. In addition to the coaxial gun, nine magnetic field coils are utilized to shape the vacuum magnetic flux. This f… more

Date: July 7, 2003

Creator: McLean, H. S.; Woodruff, S.; Hill, D. N.; Bulmer, R. H.; Cohen, B. I.; Hooper, E. B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Transport and Fluctuations in High Temperature Spheromak Plasmas

Globally coherent magnetic fluctuations often observed during the driven phase after spheromak formation in the Sustained Spheromak Physics Experiment (SSPX) can be reduced to small amplitude by programming the magnetic flux = {Psi}{sub gun} and the discharge current = I{sub gun} in the formation gun. Scanning the edge normalized current = {lambda}{sub edge} = {lambda}{sub gun} = {mu}{sub 0}I{sub gun}/{Psi}{sub gun} above and below the minimum energy eigenvalue = {lambda}{sub FC} of the flux co… more

Date: October 27, 2005

Creator: McLean, H. S.; Woodruff, S.; Wood, R. D.; Hooper, E. B.; Hill, D. N.; Moller, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A flexible software architecture for tokamak discharge control systems

The software structure of the plasma control system in use on the DIII-D tokamak experiment is described. This system implements control functions through software executing in real time on one or more digital computers. The software is organized into a hierarchy that allows new control functions needed to support the DIII-D experimental program to be added easily without affecting previously implemented functions. This also allows the software to be portable in order to create control systems … more

Date: October 1, 1996

Creator: Ferron, J. R.; Pentaflor, B.; Walker, M. L.; Moller, J. & Butner, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Modeling of current profile evolution and equilibria in negative central shear discharges in the DIII-D experiment

Recent DIII-D advanced tokamak experiments with negative central shear (NCS) have resulted in operation at high normalized {beta}, {beta}{sub N}={beta}/(I/aB), to 4.2, confinement enhancement factors to H=4 (H={tau}{sub E}/{tau}ITER-89P), and record neutron rates for DIII-D to 2.4X10{sup 16} neutrons/sec. These data were obtained during high triangularity, single and double null diverted operation with peaked (L-mode) and broad (H-mode) pressure profiles. We are modeling the spatial and tempora… more

Date: June 20, 1996

Creator: Casper, T. A.; Crotinger, J.; Meyer, W.; Moller, J.; Pearlstein, L. D.; Rice, B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Energy confinement and magnetic field generation in the SSPX spheromak

The Sustained Spheromak Physics Experiment (SSPX) [E.B. Hooper, et. al., Nuclear Fusion, Vol. 39, No. 7] explores the physics of efficient magnetic field buildup and energy confinement, both essential parts of advancing the spheromak concept. Extending the spheromak formation phase increases the efficiency of magnetic field generation with the maximum edge magnetic field for a given injector current (B/I) from 0.65 T/MA previously to 0.9 T/MA. We have achieved the highest electron temperatures … more

Date: February 11, 2008

Creator: Hudson, B.; McLean, H. S.; Wood, R. D.; Hooper, E. B.; Hill, D. N.; Jayakumar, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department