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in publisher: "General Atomics, San Diego, CA United States"

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The TITAN reversed-field-pinch fusion reactor study

This report discusses research on the titan-1 fusion power core. The major topics covered are: titan-1 fusion-power-core engineering; titan-1 divertor engineering; titan-1 tritium systems; titan-1 safety design and radioactive-waste disposal; and titan-1 maintenance procedures.

Date: January 1, 1990

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The TITAN reversed-field-pinch fusion reactor study

This report discusses the following topics: overview of titan-2 design; titan-2 fusion-power-core engineering; titan-2 divertor engineering; titan-2 tritium systems; titan-2 safety design and radioactive-waste disposal; and titan-2 maintenance procedures.

Date: January 1, 1990

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The TITAN reversed-field-pinch fusion reactor study

This paper on titan plasma engineering contains papers on the following topics: reversed-field pinch as a fusion reactor; parametric systems studies; magnetics; burning-plasma simulations; plasma transient operations; current drive; and physics issues for compact RFP reactors.

Date: January 1, 1990

Item Type: Report

Partner: UNT Libraries Government Documents Department

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q Profile evolution and enhanced core confinement of high {beta}{sub p} plasmas in DIII-D

In DIII-D the authors have investigated the long pulse evolution of high poloidal beta ({sub beta}{sub p}), double-null diverted H-mode discharges, which exhibit high bootstrap current fractions attractive for a reactor. At low currents I{sub p}, the current profile evolved over several seconds and the on-axis safety factor (q{sub 0}) increased. When q{sub 0} increased above {approximately}2, the MHD character changed from an m/n = 2/1 to an m/n = 3/1 internal kink mode, where m(n) are poloidal… more

Date: October 1, 1994

Creator: Stallard, B. W.; Casper, T. A. & Fenstermacher, M. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Helium transport and exhaust studies of H-mode discharges in the DIII-D tokamak

A collaborative program has been initiated to measure helium (He) transport and exhaust on DIII-D in L-mode, ELM-free H-mode, and ELMing H-mode. These diverted plasmas operating in enhanced confinement regimes should provide valuable information for the International Thermonuclear Experimental Reactor (ITER). To simulate the presence of He ash in DIII-D, a 50 ms He puff is injected into a DIII-D plasma, resulting in a He concentration of {approximately} 15%. The time dependence of the He densit… more

Date: December 31, 1993

Creator: Hillis, D. L.; Wade, M. R. & Hogan, J. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The Role of Shaping in Achieving High Performance in DIII-D

Experiments to study the effect of plasma shape on performance show that the high performance levels characteristic of VH-mode plasmas are only obtained for high triangularity ({delta}). A characteristic difference in central heating efficiency is observed when high and low {delta} plasmas are compared. The authors find this difference to correlate well with the attainment of Mercier stability. The core plasma for the high {delta} cases achieves Mercier stability when q{sub 0} rises above a cri… more

Date: October 1, 1994

Creator: Lazarus, E. A.; Hyatt, A. W. & Osborne, T. H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Nondimensional transport scaling in DIII-D: Bohm versus gyro-Bohm resolved

The scaling of cross-field heat transport with relative gyroradius {rho}{sub *} was measured in low (L) and high (H) mode tokamak plasmas using the technique of dimensionally similar discharges. The relative gyroradius scalings of the electron and ion thermal diffusivities were determined separately using a two-fluid transport analysis. For L-mode plasmas, the electron diffusivity scaled as {chi}{sub e}, {proportional_to} {chi}{sub B}{rho}{sub *}{sup 1.1{+-}0.3} (gyro-Bohm-like) while the ion d… more

Date: February 1, 1995

Creator: Petty, C. C.; Luce, T. C.; Burrell, K. H.; Chiu, S. C.; deGrassie, J. S.; Forest, C. B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Evidence for modified transport due to sheared E x B flows in high-temperature plasmas

Sheared mass flows are generated in many fluids and are often important for the dynamics of instabilities in these fluids. Similarly, large values of the E x B velocity have been observed in magnetic confinement machines and there is theoretical and experimental evidence that sufficiently large shear in this velocity may stabilize important instabilities. Two examples of this phenomenon have been observed in the DIII-D tokamak. In the first example, sufficient heating power can lead to the L-H … more

Date: November 1, 1994

Creator: Groebner, R. J.; Burrell, K. H. & Austin, M. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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First-wall heat-flux measurements during ELMing H-mode plasma

In this report we present measurements of the diverter heat flux in DIII-D for ELMing H-mode and radiative diverter conditions. In previous work we have examined heat flux profiles in lower single-null diverted plasmas and measured the scaling of the peak heat flux with plasma current and beam power. One problem with those results was our lack of good power accounting. This situation has been improved to better than 80--90% accountability with the installation of new bolometer arrays, and the o… more

Date: January 28, 1994

Creator: Lasnier, C. J.; Allen, S. L.; Hill, D. N.; Leonard, A. W. & Petrie, T. W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Plasma shape experiments for an optimized tokamak

In this paper we present results from recent experiments at DIII-D which measured the plasma stability and confinement performance product, {beta}{tau}{sub E}, in one previously studied and three new plasma shapes. One important goal of these experiments was to identify performance vs shape trends which would identify a shape compatible with both high performance and the planned effort to decrease the power flux to the divertor floor using a closed ``slot`` divertor geometry. power flux to the … more

Date: July 1, 1994

Creator: Hyatt, A. W.; Osborne, T. H. & Lazarus, E. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Power balance in DIII-D during single-null ELMing H-mode plasmas

We account for {ge}85% of the injected power in DIII-D during single-null diverted ELMing H-mode discharges. Core plasma radiation accounts for {le}18% with the rest flowing through the scrape-off layer to the inboard and outboard divertors. The total power roughly splits in an in:out ratio of 1:1.3. Of the power entering the outboard divertor 75% leaves as direct heat flux to the divertor target plates with the rest in the form of radiation. In the inboard divertor, however, 75% of the power l… more

Date: July 1, 1994

Creator: Leonard, A. W.; Lasnier, C. J. & Cuthbertson, J. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Enhanced Scrape-Off Layer Plasma in DIII-D Double-Null Discharges

In this paper, the authors examine a denser and broader scrape-off layer (SOL) plasma, first seen in VH mode, in the DIII-D tokamak. The enhanced SOL appears in many types of double-null (DN) discharges and is not a property of VH-mode only. The DN enhanced SOL density and temperature profiles exhibit a 5--6 cm broad profile outside the separatrix. For DN and single-null (SN) boundary geometry with similar core plasma conditions, the enhanced SOL is only observed in high triangularity discharge… more

Date: July 1, 1994

Creator: Watkins, J. G.; Jong, R. A. & Moyer, R. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Extended theory of main ion and impurity rotation and bootstrap current in a shear layer

In this paper, standard neoclassical theory has been extended into the shear layer. Main ion and impurity ion rotation velocity and bootstrap current within shear layer in H-mode are discussed. Inside the H-mode shear layer, standard neoclassical theory is not valid since the ion poloidal gyroradius becomes comparable to pressure gradient and electric field gradient scale length. To allow for arbitrary ratio of {rho}{theta}i/L{sub n} and {rho}{theta}i/L{sub Er} a new kinetic theory of main ion … more

Date: November 1, 1993

Creator: Kim, Y. B.; Hinton, F. L.; St. John, H.; Taylor, T. S. & Wroblewski, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Effect of low density H-mode operation on edge and divertor plasma parameters

We present a study of the impact of H-mode operation at low density on divertor plasma parameters on the DIII-D tokamak. The line-average density in H-mode was scanned by variation of the particle exhaust rate, using the recently installed divertor cryo-condensation pump. The maximum decrease (50%) in line-average electron density was accompanied by a factor of 2 increase in the edge electron temperature, and 10% and 20% reductions in the measured core and divertor radiated power, respectively.… more

Date: July 1, 1994

Creator: Maingi, R.; Mioduszewski, P. K. & Cuthbertson, J. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Toward a design for the ITER plasma shape and stability control system

A design strategy for an integrated shaping and stability control algorithm for ITER is described. This strategy exploits the natural multivariable nature of the system so that all poloidal field coils are used to simultaneously control all regulated plasma shape and position parameters. A nonrigid, flux-conserving linearized plasma response model is derived using a variational procedure analogous to the ideal MHD Extended Energy Principle. Initial results are presented for the non-rigid plasma… more

Date: July 1, 1994

Creator: Humphreys, D. A.; Leuer, J. A.; Kellman, A. G.; Haney, S. W.; Bulmer, R. H.; Pearlstein, L. D. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Helium exhaust studies in the DIII-D tokamak

Significant exhaust of thermal helium in a diverted, H-mode deuterium plasma has been demonstrated for the first time on the DIII-D tokamak using an in-vessel cryopump conditioned with an argon frost. The helium, introduced via gas puffing, is observed to reach the plasma core and then is readily removed from the plasma with a time constant of {approximately}8-15 energy confinement times. Detailed analysis of the helium profile evolution indicates that the exhaust rate is limited by the exhaust… more

Date: July 1, 1994

Creator: Wade, M. R.; Hogan, J. T.; Hillis, D. L.; Maingi, R.; Finkenthal, D. F.; Mahdavi, M. A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Measurements of carbon and tungsten erosion/deposition in the DIII-D divertor

Net erosion/deposition rates of carbon and tungsten were measured at the outer strike point of the divertor plasma on the floor of the DIII-D tokamak during deuterium H-mode operation at a peak power deposition of about 40 W/cm{sup 2}. For carbon, net erosion rates of up to 4 nm/s were found. For a tungsten film, no appreciable erosion was detected. However, measurements of deposited tungsten on adjacent carbon surfaces indicated a net W erosion rate of 0.06 nm/s.

Date: August 1, 1994

Creator: Bastasz, R.; Wampler, W. R.; Cuthbertson, J. W.; Buchenauer, D. A.; Brooks, N.; Junge, R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Fluctuations in high {beta}{sub p} plasmas in DIII-D

In our investigation of improved confinement in high poloidal beta ({beta}{sub p}= 2 to 4) advanced tokamak experiments, we observe that the internal MHD activity evolves from an m/n = 2/1 to a 3/1 structure coincident with q{sub o} rising above 2, and consistent with the GATO code stability analysis. The plasma eventually evolves to a quiescent state at which time the stored energy increases, mostly as a result of improved particle confinement. The bootstrap fraction rises to 80%. The measured… more

Date: July 1, 1994

Creator: Casper, T. A.; Chu, M. S. & Gohil, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Edge fluctuation measurements by phase contrast imaging on DIII-D

A novel CO{sub 2} laser phase contrast imaging diagnostic has been developed for the DIII-D tokamak, where it is being employed to investigate density fluctuations at the outer edge of the plasma. This system generates 16-point, 1-D images of a 7.6 cm wide region in the radial direction, and is characterized by long wavelength (7.6 cm) and high frequency (100 MHz) capability, as well as excellent sensitivity ({rvec n} {approx_gt} 10{sup 9} cm{sup {minus}3}). The effects of vertical line integra… more

Date: May 1, 1994

Creator: Coda, S. & Porkolab, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Benchmarking UEDGE with DIII-D data

Comparisons between a 2-D fluid simulation of the scrape-off-layer (SOL) plasma of a diverted tokamak and experimental data from the DIII-D are shown. It is concluded that a simple diffusive model for perpendicular transport is consistent with the data. Discrepancies in the simulation suggest that impurity radiation may be playing a significant role in the experiment, and that further work is required to understand hydrogen recycling at the divertor.

Date: September 1, 1993

Creator: Porter, G. D.; Fenstermacher, M.; Rensink, M. E.; Rognlien, T. D.; Groebner, R.; Leonard, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Installation and initial operation of the DIII-D advanced divertor cryocondensation pump

Phase two of a divertor cryocondensation pump, the Advanced Divertor Program, is now installed in the DIII-D tokamak at General Atomics and complements the phase one biasable ring electrode. The installation consists of a 10 m long cryocondensation pump located in the divertor baffle chamber to study plasma density control by pumping of the divertor. The design is a toroidally electrically continuous liquid helium-cooled panel with 1 m{sup 2} of pumping surface. The helium panel is single point… more

Date: October 1, 1993

Creator: Smith, J. P.; Schaubel, K. M.; Baxi, C. B.; Campbell, G. L.; Hyatt, A. W.; Laughon, G. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Recent VH-Mode Results on DIII-D

A regime of improved H-mode energy confinement, VH-mode, is obtained in the DIII-D tokamak with adequate vessel conditioning. The improved confinement in VH-mode is consistent with the extension of the region of high E {times} B velocity shear turbulence suppression zone further in from the plasma boundary. The energy confinement enhancement in VH-mode can be limited by ELMs, localized momentum transfer events, or operation at high heating power or low q. Energy confinement enhancement improves… more

Date: January 1, 1994

Creator: Osborne, T. H.; Burrell, K. H. & Carlstrom, T. N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Converter performance TFE Verification Program. Final test report

This report details TFE Verification Program, the objective, of which is to demonstrate the technology readiness of a TFE suitable for use as the basic element in a thermionic reactor with electric power output in the 0.5 to 5.0 MW(e) range, and a full-power life of 7 years. The TFE Verification Program built directly on the technology and data base developed in the 1960s and early 1970s in an AEC/NASA program, and in the SP-100 program conducted in 1983, 1984 and 1985. In the SP-100 program, t… more

Date: March 1, 1994

Item Type: Report

Partner: UNT Libraries Government Documents Department

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FWCD and ECCD experiments on DIII-D

Fast wave current drive and electron cyclotron current drive experiments have been performed on the DIII-D tokamak as part of the advanced tokamak program. The goal of this program is to develop techniques for controlling the profile of the current density in order to access regimes of improved confinement and stability. The experiments on fast wave current drive used a four strap antenna with 900 phasing between straps. A decoupler was used to help maintain the phasing, and feedback control of… more

Date: February 1, 1994

Creator: Prater, R.; Austin, M. E. & Baity, F. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department