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Your search keyword '"Brookman, M. W."' showing total 16 results
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16 results on '"Brookman, M. W."'

2. Experimental Measurement of ECH Deposition Broadening: Beyond Anomalous Transport

Author

Brookman M. W., Austin M. E., Gentle K. W., Petty C. C., Ernst D. E., Peysson Y., Decker J., and Barada K.

Subjects
Physics, QC1-999
Abstract

This work provides a first experimental measurement of broadened ECH deposition on the DIIID tokamak. As seen in theory[1] and simulation[2], refraction by edge density fluctuations shifts the path of RF waves, altering ECH and ECCD deposition. This paper reports on an initial experimental confirmation of broadened ECH deposition on DIII-D tokamak. Te measurements from a 48 channel 2nd Harmonic ECE Radiometer digitized at 500 kHz are used with a set of broadened trial ECH deposition functions to calculate time-dependent, modulation-induced heat fluxes. The fitting of convective and diffusive transport to these fluxes allows different ECH deposition profiles to be compared. The best-fit ECH deposition produces reasonable transport coefficients which compare favorably with simulation. This method is applied to a set of L- and H- mode DIII-D discharges. Accounting for diffusive, convective, and coupled transport, the ECH deposition profile is found to be 2 to 3 times wider than predicted by TORAY-GA ray tracing.

Published
2017
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5. Achievement of Reactor-Relevant Performance in Negative Triangularity Shape in the DIII-D Tokamak

Author

Austin, M. E., primary, Marinoni, A., additional, Walker, M. L., additional, Brookman, M. W., additional, deGrassie, J. S., additional, Hyatt, A. W., additional, McKee, G. R., additional, Petty, C. C., additional, Rhodes, T. L., additional, Smith, S. P., additional, Sung, C., additional, Thome, K. E., additional, and Turnbull, A. D., additional

Published
2019
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10. Non-local heat transport in Alcator C-Mod ohmic L-mode plasmas

Author

Massachusetts Institute of Technology. Department of Nuclear Science and Engineering, Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Plasma Science and Fusion Center, Gao, Chi, Rice, John E., Reinke, Matthew Logan, Howard, Nathaniel Thomas, Hubbard, Amanda E., Chilenski, Mark Alan, Walk Jr, John R., Hughes, Jerry W., Jr., Ennever, Paul Chappell, Porkolab, Miklos, White, Anne E., Sung, Choongki, Delgado-Aparicio, Luis, Baek, Seung Gyou, Rowan, William L., Greenwald, Martin J., Granetz, Robert S., Wolfe, Stephen M., Marmar, Earl S., Sun, H. J., Mikkelson, D., Brookman, M. W., Alcator C-Mod Team, Gao, Chi, Ph. D. Massachusetts Institute of Technology, Hughes, Jerry W., Massachusetts Institute of Technology. Department of Nuclear Science and Engineering, Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Plasma Science and Fusion Center, Gao, Chi, Rice, John E., Reinke, Matthew Logan, Howard, Nathaniel Thomas, Hubbard, Amanda E., Chilenski, Mark Alan, Walk Jr, John R., Hughes, Jerry W., Jr., Ennever, Paul Chappell, Porkolab, Miklos, White, Anne E., Sung, Choongki, Delgado-Aparicio, Luis, Baek, Seung Gyou, Rowan, William L., Greenwald, Martin J., Granetz, Robert S., Wolfe, Stephen M., Marmar, Earl S., Sun, H. J., Mikkelson, D., Brookman, M. W., Alcator C-Mod Team, Gao, Chi, Ph. D. Massachusetts Institute of Technology, and Hughes, Jerry W.

Abstract

Non-local heat transport experiments were performed in Alcator C-Mod ohmic L-mode plasmas by inducing edge cooling with laser blow-off impurity (CaF2) injection. The non-local effect, a cooling of the edge electron temperature with a rapid rise of the central electron temperature, which contradicts the assumption of 'local' transport, was observed in low collisionality linear ohmic confinement (LOC) regime plasmas. Transport analysis shows this phenomenon can be explained either by a fast drop of the core diffusivity, or the sudden appearance of a heat pinch. In high collisionality saturated ohmic confinement (SOC) regime plasmas, the thermal transport becomes 'local': the central electron temperature drops on the energy confinement time scale in response to the edge cooling. Measurements from a high resolution imaging x-ray spectrometer show that the ion temperature has a similar behaviour as the electron temperature in response to edge cooling, and that the transition density of non-locality correlates with the rotation reversal critical density. This connection may indicate the possible connection between thermal and momentum transport, which is also linked to a transition in turbulence dominance between trapped electron modes (TEMs) and ion temperature gradient (ITG) modes. Experiments with repetitive cold pulses in one discharge were also performed to allow Fourier analysis and to provide details of cold front propagation. These modulation experiments showed in LOC plasmas that the electron thermal transport is not purely diffusive, while in SOC the electron thermal transport is more diffusive like. Linear gyrokinetic simulations suggest the turbulence outside r/a = 0.75 changes from TEM dominance in LOC plasmas to ITG mode dominance in SOC plasmas., United States. Dept. of Energy (DoE Contract No DE-FC02-99ER54512), Oak Ridge Institute for Science and Education (DOE Fusion Energy Postdoctoral Research Program)

Published
2015

13. Non-local heat transport in Alcator C-Mod ohmic L-mode plasmas

Author

Gao, Chi, Rice, John E., Sun, H. J., Reinke, Matthew Logan, Howard, Nathaniel Thomas, Mikkelson, D., Hubbard, Amanda E., Chilenski, Mark Alan, Walk Jr, John R., Hughes, Jerry W., Jr., Ennever, Paul Chappell, Porkolab, Miklos, White, Anne E., Sung, Choongki, Delgado-Aparicio, Luis, Baek, Seung Gyou, Rowan, William L., Brookman, M. W., Greenwald, Martin J., Granetz, Robert S., Wolfe, Stephen M., Marmar, Earl S., Alcator C-Mod Team, Massachusetts Institute of Technology. Department of Nuclear Science and Engineering, Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Plasma Science and Fusion Center, Gao, Chi, Rice, John E., Reinke, Matthew Logan, Howard, Nathaniel Thomas, Hubbard, Amanda E., Chilenski, Mark Alan, Walk Jr, John R., Hughes, Jerry W., Jr., Ennever, Paul Chappell, Porkolab, Miklos, White, Anne E., Sung, Choongki, Delgado-Aparicio, Luis, Baek, Seung Gyou, Rowan, William L., Greenwald, Martin J., Granetz, Robert S., Wolfe, Stephen M., and Marmar, Earl S.

Subjects
Nuclear and High Energy Physics, Materials science, Alcator C-Mod, Physics::Plasma Physics, Pinch, Electron temperature, Plasma, Electron, Collisionality, Atomic physics, Condensed Matter Physics, Thermal diffusivity, Ohmic contact
Abstract

Non-local heat transport experiments were performed in Alcator C-Mod ohmic L-mode plasmas by inducing edge cooling with laser blow-off impurity (CaF2) injection. The non-local effect, a cooling of the edge electron temperature with a rapid rise of the central electron temperature, which contradicts the assumption of 'local' transport, was observed in low collisionality linear ohmic confinement (LOC) regime plasmas. Transport analysis shows this phenomenon can be explained either by a fast drop of the core diffusivity, or the sudden appearance of a heat pinch. In high collisionality saturated ohmic confinement (SOC) regime plasmas, the thermal transport becomes 'local': the central electron temperature drops on the energy confinement time scale in response to the edge cooling. Measurements from a high resolution imaging x-ray spectrometer show that the ion temperature has a similar behaviour as the electron temperature in response to edge cooling, and that the transition density of non-locality correlates with the rotation reversal critical density. This connection may indicate the possible connection between thermal and momentum transport, which is also linked to a transition in turbulence dominance between trapped electron modes (TEMs) and ion temperature gradient (ITG) modes. Experiments with repetitive cold pulses in one discharge were also performed to allow Fourier analysis and to provide details of cold front propagation. These modulation experiments showed in LOC plasmas that the electron thermal transport is not purely diffusive, while in SOC the electron thermal transport is more diffusive like. Linear gyrokinetic simulations suggest the turbulence outside r/a = 0.75 changes from TEM dominance in LOC plasmas to ITG mode dominance in SOC plasmas., United States. Dept. of Energy (DoE Contract No DE-FC02-99ER54512), Oak Ridge Institute for Science and Education (DOE Fusion Energy Postdoctoral Research Program)

Published
2014

14. Testing of the Prototype Receiver for ITER ECE Diagnostic.

Author

Dananil, S., Austin, M. E., Brookman, M. W., Pandya, H. K. B., and Kumar, Vinay

Subjects
ELECTRON cyclotron resonance heating, HIGH temperature plasmas, PLASMA diagnostics, ELECTRON temperature
Abstract

The Electron Cyclotron Emission (ECE) diagnostic system in ITER provides essential information for plasma control and for evaluating the plasma performance. It measures the electron temperature profile (edge/core), electron temperature fluctuations and radiated power in the electron cyclotron frequency range from the plasma. Virginia Diodes Inc. (VDI) has designed and developed a state-of-the-art prototype receiver to detect emission in the 200-300 GHz frequency range. The prototype receiver developed by VDI has been tested at DIII-D tokamak to check its performance by measuring higher frequency ECE harmonics in high temperature plasmas. Bench testing verifies the receiver’s band coverage and noise temperatures. Good sensitivity has been obtained meeting the ITER requirement. Also, the receiver performance is assessed for ITER by comparing the data from the receiver and the existing Michelson interferometer for the same DIII-D plasma shot. The measurement results show that the receiver provides accurate temperature information for the plasma emission throughout the frequency band. [ABSTRACT FROM AUTHOR]

Published
2017
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16. Variable location channels to improve efficiency and precision for direct ∇ T e measurements and high spatial resolution T e -profile measurements using electron cyclotron emission.

Author

Houshmandyar S, Austin ME, Brookman MW, Liu Y, Rowan WL, and Zhao H

Abstract

Electron cyclotron emission (ECE) diagnostics that use variable location channels based on yttrium iron garnet (YIG) bandpass filters improve the precision and the efficiency of measurements of electron temperature ( T e ) profiles and fluctuations (δ T e ). These variable frequency filters were substituted for fixed frequency filters in the intermediate frequency section to achieve the required higher resolution over a target radial range, just before the experiment. Here, we present the proof-of-principle for high temporal resolution measurement of the electron temperature gradient, via real-time slewing of a YIG filter for relocation of an ECE channel during a long pulse. The key component is the application of YIG tunable filters with their narrow bandwidth and capability for a high slew rate of their center frequency. This application permits fast relocation of the ECE channels for direct measurement of the gradient and close spacing of channels to investigate the magnetic island's dynamic behavior.

Published
2018
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