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Design and operation of the pellet charge exchange diagnostic for measurement of energetic confined alphas and tritons on TFTR

Description: Radially-resolved energy and density distributions of the energetic confined alpha particles in D-T experiments on TFTR are being measured by active neutral particle analysis using low-Z impurity pellet injection. When injected into a high temperature plasma, an impurity pellet (e.g. Lithium or Boron) rapidly ablates forming an elongated cloud which is aligned with the magnetic field and moves with the pellet. This ablation cloud provides a dense target with which the alpha particles produced i… more
Date: May 1, 1996
Creator: Medley, S. S.; Duong, H. H. & Fisher, R. K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Measurements of confined alphas and tritons in the MHD quiescent core of TFTR plasmas using the pellet charge exchange diagnostic

Description: The energy distributions and radial density profiles of the fast confined trapped alpha particles in DT experiments on TFTR are being measured in the energy range 0.5--3.5 MeV using a Pellet Charge eXchange (PCX) diagnostic. A brief description of the measurement technique which involves active neutral particle analysis using the ablation cloud surrounding an injected impurity pellet as the neutralizer is presented. This paper focuses on alpha and triton measurements in the core of MHD quiescen… more
Date: May 1, 1996
Creator: Medley, S. S.; Budny, R. V. & Mansfield, D. K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Measurements of energetic confined alphas and tritons on TFTR

Description: In a collaboration involving General Atomics, the A. F. Ioffe Physical-Technical Institute, and the Princeton Plasma Physics Laboratory, the energy distribution of the fast-confined alpha particles in DT experiments on TFIR is being measured by active neutral particle analysis using the ablation cloud surrounding an injected impurity pellet as the neutralizer. Recent papers reported the first measurements of the energy distribution fast confined alpha particles and examined the influence of mag… more
Date: August 1, 1995
Creator: Medley, S. S.; Duong, H. H. & McChesney, J. M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Ion temperature by charge exchange neutral analysis from vertical sightlines on the Tokamak Fusion Test Reactor

Description: The Fokker-Planck code FPPRF is used to calculate the expected deuterium charge exchange flux along vertical sighlines from TFTR neutral-beam-injected discharges. The feasibility of obtaining central ion temperature measurements by fitting the spectra obtained from these sightlines at two energy regions--above the highest neutral beam injection energy (> 100 keV) and from 20-80 keV--is investigated. It is demonstrated that the central ion temperature can be obtained from the central vertical sl… more
Date: December 1, 1987
Creator: Fiore, C. L.; Medley, S. S.; Hammett, G. W.; Kaita, R. & Scott, S. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Fusion gamma diagnostics

Description: Nuclear reactions of interest in fusion research often possess a branch that yields prompt emission of gamma radiation in excess of 15 MeV. This branch can be exploited to provide a new fusion reaction diagnostic having applications similar to conventional neutron emission measurements. Conceptual aspects of fusion gamma diagnostics are discussed with emphasis on application to TFTR during deuterium neutral beam heating of D-T and D-/sup 3/He plasmas. Recent measurements of the D(T, ..gamma..)/… more
Date: December 1, 1984
Creator: Medley, S. S.; Cecil, F. E.; Cole, D.; Conway, M. A. & Wilkinson, F. J., III
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Summary of Alpha Particle Transport

Description: This paper summarizes the talks on alpha particle transport which were presented at the 5th International Atomic Energy Agency's Technical Committee Meeting on "Alpha Particles in Fusion Research" held at the Joint European Torus, England in September 1997.
Date: August 19, 1998
Creator: Medley, S. S.; White, R. B. & Zweben, S. J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Survey of features in radiative power loss profiles in TFTR

Description: Although the total radiated power in TFTR is often as high as 70% of the heating power, most of the radiation is concentrated near the surface of the plasma, and the interior loss is almost negligible. Fractional radiation loss declines during neutral beam heating. As the high-density limit is approached, under practically any conditions, a bright band of radiation (''marfe'') appears on the inner side of the plasma column. Marfe evolution has been tracked for various conditions of heating, mag… more
Date: June 1, 1988
Creator: Schivell, J.; Bush, C. E.; Mansfield, D. K.; Medley, S. S.; Park, H. K. & Stauffer, F. J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Prompt Loss of Energetic Ions during Early Neutral Beam Injection in the National Spherical Torus Experiment

Description: Early neutral-beam injection is used in the National Spherical Torus Experiment (NSTX) to heat the electrons and slow current penetration which keeps q(0) elevated to avoid deleterious MHD activity and at the same time reduces Ohmic flux consumption, all of which aids long-pulse operation. However, the low plasma current (I{sub p} {approx} 0.5 MA) and electron density (n{sub e} {approx} 1 x 10{sup 13} cm{sup -3}) attending early injection lead to elevated orbit and shine through losses. The inh… more
Date: March 25, 2005
Creator: Medley, S. S.; Darrow, D. S.; Liu, D. & Roquemore, A. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Confinement of Neutral Beam Ions in the National Spherical Torus Experiment

Description: The loss of neutral-beam ions to the wall has been measured in the National Spherical Torus Experiment (NSTX) by means of thermocouples, an infrared (IR) camera, and a Faraday cup probe. The losses tend to exhibit the expected dependences on plasma current, tangency radius of the injector, and plasma outer gap. However, the thermocouples and the Faraday cups indicate substantially different levels of loss and this difference has yet to be understood.
Date: December 18, 2001
Creator: Darrow, D. S.; Medley, S. S.; Roquemore, A. L. & Rosenberg, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Ion Temperature from Tangential Charge Exchange Neutral Analysis on the Tokamak Fusion Test Reactor

Description: Fokker-Planck simulations of the Tokamak Fusion Test Reactor (TFTR) energetic ion mode discharges were performed to evaluate the utility of deriving the central ion temperature, T/sub i/, from deuterium neutral beam charge exchange spectra above the neutral beam injection energy. The T/sub i/ values obtained from fitting the calculated spectra obtained from sightlines nearly tangent to the neutral beam injection radius reproduce the central ion temperature within +-10% over the full range of TF… more
Date: September 1, 1987
Creator: Fiore, C. L.; Medley, S. S.; Hammett, G. W.; Kaita, R.; Roquemore, A. L. & Scott, S. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Energetic Ion Behavior in the National Spherical Torus Experiment

Description: The National Spherical Torus Experiment (NSTX) is a low aspect ratio (R/a approximately equal to 1.3) device with auxiliary heating from neutral beam injection (NBI) and high harmonic fast wave (HHFW) heating. Typical NSTX parameters are R(sub)0 = 85 cm, a = 67 cm, I(sub)p less than or equal to 1.5 MA, B(sub)T = 0.3-0.6 T. Three co-directed deuterium neutral beam sources have injected P(sub)NB less than or equal to 6.2 MW at energies E(sub)b less than or equal to 100 keV. HHFW heating has deliv… more
Date: June 26, 2003
Creator: Medley, S. S.; Bell, R. E.; Fredrickson, E. D. & Roquemore, A. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Neutral Particle Analyzer Measurements of Ion Behavior in NSTX

Description: Initial results obtained with the Neutral Particle Analyzer (NPA) diagnostic on the National Spherical Torus Experiment (NSTX) are presented. Magnetohydrodynamic activity and reconnection events cause depletion of the deuterium energetic ion distribution created by neutral-beam injection. Adding High Harmonic Fast Wave Heating to neutral-beam-heated discharges results in the generation of an energetic ion tail above the beam injection energy. NPA measurements of the residual hydrogen ion temper… more
Date: February 6, 2002
Creator: Medley, S. S.; Bell, R. E.; Darrow, D. S. & Roquemore, A. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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NSTX Diagnostics and Operation: Status and Plans

Description: The low aspect ratio and low magnetic field of the National Spherical Torus Experiment (NSTX) create many challenges for plasma diagnostics and control, as well as opportunities for studying new plasma phenomena. This paper describes the diagnostics now installed for studies of confinement, stability and edge plasma phenomena, and some of the diagnostic developments planned for the near future. The design of the plasma control system and plans for its development are also presented.
Date: August 30, 2001
Creator: Bell, M. G.; Bell, R. E.; LeBlanc, B. P. & Medley, S. S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Neutral beam interlock system on TFTR using infrared pyrometry

Description: Although the region of the TFTR vacuum vessel wall which is susceptible to damage by neutral beam strike is armored with a mosaic of TiC-clad POCO graphite titles, at power deposition levels above 2.5 kW/cm/sup 2/ the armor surface temperature exceeds 1200/sup 0/C within 250 ms and itself becomes susceptible to damage. In order to protect the wall armor, a neutral beam interlock system based on infrared pyrometry measurement of the armor surface temperature was installed on TFTR. For each beaml… more
Date: June 1, 1986
Creator: Medley, S. S.; Kugel, H. W.; Kozub, T. A.; Lowrance, J. L.; Mastrocola, V.; Renda, G. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Reconciliation of Measured and TRANSP-calculated Neutron Emission Rates in the National Spherical Torus Experiment: Circa 2002-2005

Description: A change in the response of the neutron detectors on the National Spherical Torus Experiment occurred between the 2002-2003 and 2004 experimental run periods. An analysis of this behavior by investigating the neutron diagnostic operating conditions and comparing measured and TRANSP-calculated neutron rates is presented. Also a revised procedure for cross calibration of the neutron scintillator detectors with the fission chamber detectors was implemented that delivers good agreement amongst the … more
Date: June 15, 2005
Creator: Medley, S. S.; Darrow, D. S. & Roquemore, A. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Mode particle resonances during near-tangential neutral beam injection in large tokamaks

Description: Coherent magnetohydrodynamic modes have been observed during neutral beam injection in TFTR and JET. Periodic bursts of oscillations were detected with several plasma diagnostics, and Fokker-Planck calculations show that the populations of trapped particles in both tokamaks are sufficient to account for fishbone destabilization. Estimates of mode parameters are in reasonable agreement with the experiments, and they indicate that the fishbone mode may continue to affect the performance of intens… more
Date: January 1, 1988
Creator: Kaita, R.; White, R. B.; Morris, A. W.; Fredrickson, E. D.; McGuire, K. M.; Medley, S. S. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Solid State Neutral Particle Analyzer Array on NSTX

Description: A Solid State Neutral Particle Analyzer (SSNPA) array has been installed on the National Spherical Torus Experiment (NSTX). The array consists of four chords viewing through a common vacuum flange. The tangency radii of the viewing chords are 60, 90, 100, and 120 cm. They view across the three co-injection neutral beam lines (deuterium, 80 keV (typ.) with tangency radii 48.7, 59.2, and 69.4 cm) on NSTX and detect co-going energetic ions. A silicon photodiode used was calibrated by using a mono-… more
Date: May 13, 2004
Creator: Shinohara, K.; Darrow, D. S.; Roquemore, A. L.; Medley, S. S. & Cecil, F. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Initial Neutral Particle Analyzer Measurements of Ion Temperature in NSTX

Description: The Neutral Particle Analyzer (NPA) diagnostic on the National Spherical Torus Experiment (NSTX) utilizes a PPPL-designed E||B spectrometer which measures the energy spectra of minority H and bulk D species simultaneously with 39 energy channels per mass specie and a time resolution of 1 msec. The calibrated energy range is E = 0.5-150 keV and the energy resolution varies from (delta)E/E = 3-7% over the surface of the microchannel plate detector. The NPA measures thermal Maxwellian ion spectra … more
Date: July 8, 2002
Creator: Medley, S. S.; Bell, R. E.; Petrov, M. P.; Roquemore, A. L. & Suvorkin, E. V.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Neutral Beam Ion Confinement in NSTX

Description: Neutral-beam (NB) heating in the National Spherical Torus Experiment (NSTX) began in September 2000 using up to 5 MW of 80 keV deuterium (D) beams. An initial assessment of beam ion confinement has been made using neutron detectors, a neutral particle analyzer (NPA), and a Faraday cup beam ion loss probe. Preliminary neutron results indicate that confinement may be roughly classical in quiescent discharges, but the probe measurements do not match a classical loss model. MHD activity, especially… more
Date: July 24, 2001
Creator: Darrow, D. S.; Fredrickson, E. D.; Kaye, S. M.; Medley, S. S. & Roquemore, A. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Alpha Particle Physics Experiments in the Tokamak Fusion Test Reactor

Description: Alpha particle physics experiments were done on the Tokamak Fusion Test Reactor (TFTR) during its deuterium-tritium (DT) run from 1993-1997. These experiments utilized several new alpha particle diagnostics and hundreds of DT discharges to characterize the alpha particle confinement and wave-particle interactions. In general, the results from the alpha particle diagnostics agreed with the classical single-particle confinement model in magnetohydrodynamic (MHD) quiescent discharges. Also, the ob… more
Date: December 14, 1998
Creator: Budny, R. V.; Darrow, D. S.; Medley, S. S.; Nazikian, R. & Zweben, S. J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Periscope-camera system for visible and infrared imaging diagnostics on TFTR

Description: An optical diagnostic consisting of a periscope which relays images of the torus interior to an array of cameras is used on the Tokamak Fusion Test Reactor (TFTR) to view plasma discharge phenomena and inspect vacuum vessel internal structures in both visible and near-infrared wavelength regions. Three periscopes view through 20-cm-diameter fused-silica windows which are spaced around the torus midplane to provide a viewing coverage of approximately 75% of the vacuum vessel internal surface are… more
Date: May 1, 1985
Creator: Medley, S. S.; Dimock, D. L.; Hayes, S.; Long, D.; Lowrence, J. L.; Mastrocola, V. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Global Confinement, Sawtooth Mixing, and Stochastic Diffusion Ripple Loss of Fast ICRF-driven H+ Minority Ions in TFTR

Description: This paper presents studies of ICRF-driven H+ minority ions in TFTR (Tokamak Fusion Test Reator) deuterium plasmas using primarily passive Ho flux detection in the energy range of 0.2-1.0 MeV with some corroborating active (lithium pellet charge exchange) measurements. It is shown that in the passive mode the main donors for the neutralization of H+ ions in this energy range are C5+ ions. The measured effective H+ tail temperatures range from 0.15 MeV at an ICRF power of 2 MW to 0.35 MeV at 6 M… more
Date: July 1, 1998
Creator: Petrov, M. P.; Bell, R.; Budny, R. V.; Gorelenkov, N. N.; Medley, S. S. & Zweben, S. J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Power and particle balance during neutral beam injection in TFTR

Description: Detailed boundary plasma measurements on TFTR have been made during a NBI power scan in the range P{sub tot} {equals} 1MW--20MW in the L-mode regime. The behavior of the plasma density {l angle}n{sub e}{r angle}, radiated power P{sub rad}, carbon and deuterium fluxes {Gamma}{sub C}, {Gamma}{sub D}, and {Zeta}{sub eff} can be summarized as, {l angle}n{sub e}{r angle} {proportional to} P{sub tot}{sup {1/2}}, P{sub rad}, {Gamma}{sub C}, {Gamma}{sub D} {proportional to} P{sub tot}, and {Zeta}{sub e… more
Date: May 1, 1991
Creator: Pitcher, C. S.; Budny, R. V.; Hill, K. W.; Kilpatrick, S. J.; Manos, D. M.; Medley, S. S. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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