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Modeling and optimization of a test-cell upgrade for MFTF-B operating in the high neutron wall loading mode

Description: Models of the plasma particle and power balances in a tandem mirror with a high-field test-cell insert in the central cell have been used to calculate operating points for test-cell upgrades of the MFTF-B configuration. The code results have been benchmarked against the proposal plasma parameters for the MFTF-..cap alpha..+T configuration operating in the high neutron wall loading mode. Some parametric studies have been done. Using the results from these parametrics an optimized set of operating parameters for an MFTF-..cap alpha..+T-like configuration with a test-cell which will accommodate two 1.5 m long blanket test modules has been generated. This operating point has the same test-cell neutron wall loading as the original configuration and lower input powers to other systems in the device. The neutral beam power per unit blanket module length is also somewhat reduced in the optimized case.
Date: April 3, 1985
Creator: Fenstermacher, M.E.
Partner: UNT Libraries Government Documents Department

Modeling and optimization of operating parameters for a test-cell option of the Fusion Power Demonstration-II tandem mirror design

Description: Models of tandem mirror devices operated with a test-cell insert have been used to calculate operating parameters for FPD-II+T, an upgrade of the Fusion Power Demonstration-II device. Two test-cell configurations were considered, one accommodating two 1.5 m blanket test modules and the other having four. To minimize the cost of the upgrade, FPD-II+T utilizes the same coil arrangement and machine dimensions outside of the test cell as FPD-II, and the requirements on the end cell systems have been held near or below those for FPD-II. The maximum achievable test cell wall loading found for the short test-cell was 3.5 MW/m/sup 2/ while 6.0 MW/m/sup 2/ was obtainable in the long test-cell configuration. The most severe limitation on the achievable wall loading is the upper limit on test-cell beta set by MHD stability calculations. Modification of the shape of the magnetic field in the test-cell by improving the magnet design could raise this beta limit and lead to improved test-cell performance.
Date: April 3, 1985
Creator: Haney, S.W. & Fenstermacher, M.E.
Partner: UNT Libraries Government Documents Department

Test cell modeling and optimization for FPD-II

Description: The Fusion Power Demonstration, Configuration II (FPD-II), will ba a DT burning tandem mirror facility with thermal barriers, designed as the next step engineering test reactor (ETR) to follow the tandem mirror ignition test machines. Current plans call for FPD-II to be a multi-purpose device. For approximately the first half of its lifetime, it will operate as a high-Q ignition machine designed to reach or exceed engineering break-even and to demonstrate the technological feasibility of tandem mirror fusion. The second half of its operation will focus on the evaluation of candidate reactor blanket designs using a neutral beam driven test cell inserted at the midplane of the 90 m long cell. This machine called FPD-II+T, uses an insert configuration similar to that used in the MFTF-..cap alpha..+T study. The modeling and optimization of FPD-II+T are the topic of the present paper.
Date: April 10, 1985
Creator: Haney, S.W. & Fenstermacher, M.E.
Partner: UNT Libraries Government Documents Department

Physics modeling of tandem mirror devices with high-field test cell inserts

Description: Recently developed plasma physics models of tandem mirror operation with a high-field technology test cell insert in the central cell are described in detail. These models have been incorporated in the TMRBAR tandem mirror reactor physics code. Results of a benchmark case for the code models against previous analysis of the MFTF - ..cap alpha.. /sup +/ T configuration are given. A brief users guide to the new TMRBAR with the test cell models is also presented. Some description of the applications of the models to MFTF - ..cap alpha.. /sup +/ T and FPD - II + T configurations is made. References are given to separate reports on these studies.
Date: April 15, 1985
Creator: Fenstermacher, M.E. & Campbell, R.B.
Partner: UNT Libraries Government Documents Department

Plasma engineering models of tandem mirror devices with high-field test-cell inserts

Description: Plasma physics and engineering models of tandem mirror devices operated with a high-field technology test-cell insert in the central cell, which have been incorporated recently in the TMRBAR tandem mirror reactor physics code, are described. The models include particle and energy balance in the test-cell region as well as the interactions between the test-cell particles and those flowing through the entire device. The code calculations yield consistent operating parameters for the test-cell, central cell, and end cell systems. A benchmark case for the MFTF-..cap alpha..+T configuration is presented which shows good agreement between the code results and previous calculations.
Date: April 3, 1985
Creator: Fenstermacher, M.E. & Campbell, R.B.
Partner: UNT Libraries Government Documents Department

Options for axisymmetric operation of MFTF-B

Description: The flexibility of MFTF-B for axisymmetric experiments has been investigated. Interhcanging the axicell coils and increasing their separation results in an axisymmetric plug cell with 12:1 and 6:1 inner and outer mirror ratios, respectively. For axisymmetric operation, the sloshing-ion neutral beams, ECRH gyrotrons, and the pumping system would be moved to the axicell. Stabilization by E-rings could be explored in this configuration. With the addition of octopole magnets, off-axis multipole stabilization could also be tested. Operating points for octopole and E-ring-stabilized configurations with properties similar to those of the quadrupole MFTF-B, namely T/sub ic/ = 10 - 15 keV and n/sub c/ approx. = 3 x 10/sup 13/ cm/sup -3/, have been obtained. Because of the negligible radial transport of central-cell ions, the required neutral-beam power in the central cell has been dramatically reduced. In addition, because MHD stabilization is achieved by off-axis hot electrons in both cases, much lower barrier beta is possible, which aids in reducing the barrier ECRH power. Total ECRH power in the end cell is projected to be approx. =1 MW. Possible operating points for both octopole and E-ring configurations are described along with the stability considerations involved.
Date: March 30, 1986
Creator: Fenstermacher, M.E.; Devoto, R.S. & Thomassen, K.I.
Partner: UNT Libraries Government Documents Department

TIBER II (Tokamak Ignition/Burn Experimental Reactor) parameters with neutral beams at high energies

Description: The baseline neutral beam energy for TIBER II was chosen to be 500 keV consistent with the use of near term dc acceleration technology. Adequate penetration to the axis for core current drive in larger ETR devices requires higher beam energies. However, beam instabilities may limit the current drive efficiency at high energy to lower values than predicted classically. The characteristics of TIBER II and a device with 4.5 m major radius as functions of beam energy are presented. 11 refs.
Date: October 16, 1987
Creator: Devoto, R.S.; Fenstermacher, M.E. & Papanikolaou, P.G.
Partner: UNT Libraries Government Documents Department

Experimental and Numerical Studies of Separatrix Splitting and Magnetic Footprints in DIII-D

Description: A numerical field line integration code is used to study the structure of divertor footprints produced by small non-axisymmetric magnetic perturbation in the DIII-D tokamak. The numerical modeling results are compared to experimental infrared camera data which show a splitting of the divertor target plate heat flux into several distinct peaks when an n=3 magnetic perturbation from the DIII-D I-coil is applied. The heat flux splitting consistently appears when the n=3 perturbation is applied and disappears when the perturbation is removed. The magnitude of the splitting implied by the numerical modeling is a factor of 3 smaller than the splitting seen in the experimental data. These results suggest that the plasma response to the edge resonant applied n=3 magnetic perturbation produces an amplification of the vacuum magnetic footprint structure on the divertor target plates. These results may have significant implications for the ITER divertor design.
Date: May 15, 2006
Creator: Evans, T; Joseph, I; Moyer, R; Fenstermacher, M; Lasnier, C & Yan, L
Partner: UNT Libraries Government Documents Department

A tangentially viewing visible TV system for the DIII-D divertor

Description: A video camera system has been installed on the DIII-D tokamak for 2-D spatial studies of line emission in the lower divertor region. The system views the divertor tangentially from an outer port at approximately the height of the X-point. At the tangency plane the entire divertor from inner wall to outside the DIII-D bias ring is viewed with spatial resolution of approximately 1 cm. The image contains information from approximately 90 degrees of toroidal angle. In a recent upgrade, remotely controllable filter changers were added which have produced images from nominally identical shots using a series of spectral lines. Software was developed to calculate the response function matrix using distributed computing techniques and assuming toroidal symmetry. Standard sparse matrix algorithms are then used to invert the 3-D images onto a poloidal plane. Spatial resolution of the inverted images is 2 cm; higher resolution simply increases the size of the response function matrix. Initial results from a series of experiments with multiple identical shots show that the emission from CII and CIII, which appears along the inner scrape-off layer above and below the X-point during ELMing H-mode, moves outward and becomes localized near the X-point in Partially Detached Divertor (PDD) operation.
Date: February 1, 1996
Creator: Fenstermacher, M.E.; Meyer, W.H. & Wood, R.D.
Partner: UNT Libraries Government Documents Department

Evolution of 2D deuterium and impurity radiation profiles during transitions from attached to detached divertor operation in DIII-D

Description: This paper presents the detailed evolution of conditions along both the inner and outer divertor legs during the transition from attached ELMing H-mode to partially detached divertor (PDD) operation in DIII-D. Visible emission profiles in a poloidal plane show that in ELMing H-mode prior to deuterium gas injection, CIII emission peaks in the inner SOL near the X-point and deuterium emission (from ionization and recombination) peaks at the inner target plate near the inner strike point (ISP). The spatial profiles of the recombination and ionization zones, determined by forming images of the ratio of intensities from simultaneous images of D{sub {alpha}} and D{sub {gamma}} emission, show that recombination dominates the inner leg emission near the target; ionization dominates in a poloidally narrow zone upstream in the inner leg. After deuterium injection, when the PDD transition begins, the profiles of carbon visible emission show first an increase in the inner SOL near the X-point, followed by increases in emission in the lower regions of the outer leg. Deuterium emission at the transition onset decreases at th4e ISP and increases across the private flux region below the X-point. As the transition to PDD conditions proceeds the deuterium emission increases in the private flux region; recombination dominates near the floor and ionization higher near the X-point. Carbon emission appears along both divertor legs and at the X-point. In the final quasi-steady PDD state, the recombination emission in the outer leg is near the separatrix and along the target plate; emission from collisional excitation dominates in the upper part of the outer leg just below the X-point, and carbon emission is localized at the X-point. These results suggest that transport of neutral deuterium between the inner and outer divertor legs through the private flux region plays an important role in the initiation of outer ...
Date: August 1, 1998
Creator: Fenstermacher, M.E.; Allen, S.L. & Hill, D.N.
Partner: UNT Libraries Government Documents Department

Studies of high-{delta} (baffled) and low-{delta} (open) pumped divertor operation on DIII-D

Description: The authors report new experimental results with the RDP-OB (Radiative Divertor Project-outer baffle) and cryopump in both upper single-null (USN) and double-null (DN) ELMing H-mode discharges. The baffled divertor reduced the core ionization ({approximately}2--2.5{times}), in reasonable agreement with predictions from UEDGE/DEGAS modeling ({approximately}3.75{times}). The upper cryopump achieved density control of n{sub e}/n{sub gw} {approximately} 0.22 (line density/Greenwald density) with Z{sub eff} {approximately} 2 in high-{delta} plasmas. The measured exhaust is comparable to the lower pump, except at lower core electron densities (n{sub e} < 5 {times} 10{sup 19} m{sup {minus}3}). Efficient impurity exhaust was obtained with deuterium SOL flow. Preliminary experiments with DN operation has shown that the particle exhaust to the upper pump depends on the up/down magnetic balance. Preliminary experiments indicate that the DN exhaust is roughly 40--50% of the USN exhaust at n{sub e} {approximately} 4 {times} 10{sup 19} m{sup {minus}3}.
Date: August 1, 1998
Creator: Allen, S. L.; Fenstermacher, M. E. & Greenfield, C. M.
Partner: UNT Libraries Government Documents Department

A comprehensive 2-D divertor data set from DIII-D for edge theory validation

Description: A comprehensive set of experiments has been carried out on the DIII-D tokamak to measure the 2-D (R,Z) structure of the divertor plasma in a systematic way using new diagnostics. Measurements cover the divertor radially from inside the X-point to the outer target plate and vertically from the target plate to above the X-point. Identical, repeatable shots were made, each having radial sweeps of the X-point and divertor strike points, to allow complete plasma and radiation profile measurements. Data have been obtained in ohmic, L-mode, ELMing H-mode, and reversed B{sub T} operation ({gradient}B drift away from the X-point). In addition, complete measurements were made of radiative divertor plasmas with a Partially Detached Divertor (PDD) induced by D{sub 2} injection and with a Radiating Mantle induced by Impurity injection (RMI) using neon and nitrogen. The data set includes first observations of the radial and poloidal profiles of the X-point, inner and outer leg plasmas in PDD and RMI radiative divertor operation. Preliminary data analysis shows that intrinsic impurities play a critical role in determining the SOL and divertor conditions.
Date: February 1, 1996
Creator: Fenstermacher, M.E.; Allen, S.L. & Hill, D.N.
Partner: UNT Libraries Government Documents Department

Carbon influx in He and D plasmas in DIII-D

Description: Differences in the carbon behavior between He and D plasmas during VH-mode, L-mode and L-mode with excess gas puffing are reported and inferences on the importance of the various carbon sources during these modes of operation are discussed. During a VH-mode phase, VUV and visible charge exchange spectroscopy indicates that for both He and D operation the carbon behavior is very similar. In the edge plasma, carbon build up is quite rapid, and the carbon influx represents a large fraction of the total plasma density increase until the termination of the VH phase. During cold divertor operation induced by puffing the primary fueling gas, D and He discharges show a difference in the carbon behavior. The core carbon density is seen to be approximately constant during a D discharge as it transitions from an attached to a cold divertor. However in a He discharge, the core carbon density disappears soon after the cold divertor transition. Arguments are made that the primary carbon source in the ELM free H-mode period is physical sputtering by ion impact at the divertor strike point. In L-mode, both attached and cold divertor, the primary source is from the divertor region and two possibilities for this source are chemical sputtering or charge neutral sputtering. Existing data supports charge exchange neutrals as dominant.
Date: July 1998
Creator: West, W.P.; Brooks, N.H. & Fenstermacher, M.E.
Partner: UNT Libraries Government Documents Department

Simulation of experimentally achieved detached plasmas using the UEDGE code

Description: The introduction of a divertor Thomson scattering system in DIII-D has enabled accurate determination of the plasma properties in the divertor region. We identify two plasma regimes; detached and attached. The electron temperature in the detached regime is about 2 eV, much lower than 5 to 10 eV determined earlier. We show that fluid models of the DIII-D scrape-off layer plasma are able to reproduce many of the features of these two plasma regimes, including the boundaries for transition between them. Detailed comparison between the results obtained from the fluid models and experiment suggest the models underestimate the spatial extent of the low temperature region associated the detached plasma mode. We suggest that atomic physics processes at the low electron temperatures reported here may account for this discrepancy.
Date: October 30, 1995
Creator: Porter, G.D.; Allen, S. & Fenstermacher, M.
Partner: UNT Libraries Government Documents Department

Plasma parameters for alternate operating modes of TIBER-II

Description: Parameters for operating points of TIBER-II, different from the baseline steady-state operation, are presented. These results have been generated with the MUMAK tokamak power balance code. Pulsed ignited and high performance steady-state operating points are described. 20 refs.
Date: October 16, 1987
Creator: Fenstermacher, M.E.; Devoto, R.S.; Logan, B.G. & Perkins, L.J.
Partner: UNT Libraries Government Documents Department

Modeling of LH current drive in self-consistent elongated tokamak MHD equilibria

Description: Calculations of non-inductive current drive typically have been used with model MHD equilibria which are independently generated from an assumed toroidal current profile or from a fit to an experiment. Such a method can lead to serious errors since the driven current can dramatically alter the equilibrium and changes in the equilibrium B-fields can dramatically alter the current drive. The latter effect is quite pronounced in LH current drive where the ray trajectories are sensitive to the local values of the magnetic shear and the density gradient. In order to overcome these problems, we have modified a LH simulation code to accommodate elongated plasmas with numerically generated equilibria. The new LH module has been added to the ACCOME code which solves for current drive by neutral beams, electric fields, and bootstrap effects in a self-consistent 2-D equilibrium. We briefly describe the model in the next section and then present results of a study of LH current drive in ITER. 2 refs., 6 figs., 2 tabs.
Date: May 9, 1989
Creator: Blackfield, D.T.; Devoto, R.S.; Fenstermacher, M.E.; Bonoli, P.T.; Porkolab, M. & Yugo, J.
Partner: UNT Libraries Government Documents Department

Performance analyses of Elmo Bumpy Torus plasmas and plasma support systems

Description: The development and applcation of the OASIS Code (Operational Analysis of ELMO Bumpy Torus Support and Ignition Systems) for the study of EBT device and plasma performance are presented. The code performs a time-independent, zero-dimensional self-consistent calculation of plasma and plasmasupport systems parameters for the physics and engineering of EBT devices. The features of OASIS modeling for the EBT plasma include: (1) particle balance of the bulk toroidal and electron ring plasma components for experimental (H-H, D-D, He-He etc.) as well as reactor (D-T) devices; (2) energy balance in the bulk and ring plasmas for externally heated or ignition devices; (3) alpha particle effects for reactor devices; (4) auxiliary heating effects, including microwave (ECRH), RF heating (e.g., ICRH), and neutral beam methods; and (5) ignition conditions, including fusion power, alpha power and neutron wall loading. The performance studies using OASIS focussed on variation in plasma and device size and on microwave input power and frequency. An additional study was performed to determine the characteristics of an EBT reactor proof-of-principle device operated with a deuterium-tritium plasma. Sensitivity studies were performed for variation in the input microwave power sharing fractions and the dependence of the bulk n tau scaling law on bulk electron temperature.
Date: December 31, 1979
Creator: Fenstermacher, M. E.
Partner: UNT Libraries Government Documents Department

Optimized multi-modal-operation designs for ITER (International Thermonuclear Experimental Reactor)

Description: The tokamak nonlinear optimization systems code TETRA has been expanded to contain the option of examining machine designs capable of ''multi-modal'' operations. The conceptual International Thermonuclear Experimental Reactor (ITER) is an example of a ''bi-modal'' operating machine design in that it must be capable of both pulse-ignited and steady-state operations. This new version of TETRA allows for the optimization of a ''figure-of-merit'' which may involve several operating scenarios. We obtain for ITER minimum cost designs which are capable of igniting when operated in the pulsed mode as well as have reasonable Q > 5 when operated in steady-state. 3 refs., 3 tabs.
Date: October 7, 1988
Creator: Blackfield, D.T.; Perkins, L.J.; Devoto, R.S.; Fenstermacher, M.E. & Ho, S.K.
Partner: UNT Libraries Government Documents Department

Computation of lower hybrid, neutral beam and bootstrap currents in consistent MHD equilibria

Description: A possible scenario for steady state current drive in large, high- temperature tokamaks includes current driven by lower hybrid (LH) waves in the outer region with high-energy neutral beams (NB) used for current drive in the core. In addition, provided the poloidal beta is sufficiently high, there can be substantial bootstrap (BS) current, as observed in the TFTR and JET experiments. In work reported previously, a computer code, ACCOME, was written to obtain a solution to the MHD equations which is consistent with current driven by neutral beams, electric fields, and neoclassical (bootstrap) effects. For the computation of the solution to the Grad-Shafranov equation, the SELENE code is used. Iteration is necessary between SELENE and the current-drive computations to obtain a consistent solution. In this paper we describe modifications to ACCOME to enable the computation of LH current in addition to the NB, BS, and OH currents. The next section describes the models used and then the final section presents an application to ITER. 4 refs., 4 figs.
Date: February 1, 1989
Creator: Devoto, R.S.; Blackfield, D.T.; Fenstermacher, M.E.; Bonoli, P.T. & Porkolab, M.
Partner: UNT Libraries Government Documents Department

Electron cyclotron resonance heating in the microwave tokamak experiment

Description: This paper presents the results from a series of Electron Cyclotron Resonance Heating (ECRH) experiments on the Microwave Tokamak Experiment (MTX). On-axis heating at B{sub T} = 5T (f{sub ce} = 140 GHz) has been performed at electron densities up to cutoff. We have used both a long-pulse gryotron ({approximately}200 kW, {approximately}0.1s) and a pulsed Free Electron Laser (FEL) as microwave sources. Gyrotron experiments with power densities corresponding to 4 MW m{sup {minus}3}. A far infrared (FIR) polarimeter measured peaking of plasma current profiles in some discharges during the ECRH pulse. During high-power single-pulse FEL experiments, single-pass microwave !transmission measurements show nonlinear effects; i.e., higher transmission than predicted by linear theory. A corrugated-wall duct was used in the tokamak port to increase the gradient of the parallel refractive index n{sub parallel} of the incident wave, and increased absorption was observed. Evidence of electron tail heating during FEL pulses was observed on soft x-ray and ECE diagnostics. These results are in agreement with predictions of nonlinear theory; extrapolation of this theory to reactor-like conditions indicates efficient absorption and heating. A Laser Assisted Particle Probe Spectroscopy (LAPPS) diagnostic provided estimates of the vacuum electric field of the FEL which were consistent with the measured power. Multiple pulse operation of the ETA-II accelerator for the FEL has also been demonstrated, indicating the feasibility of high-average power FEL operation.
Date: September 1, 1992
Creator: Allen, S. L.; Casper, T. A. & Fenstermacher, M. E.
Partner: UNT Libraries Government Documents Department

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

Description: 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 (toroidal) mode numbers, which then disappeared with further increases in q{sub 0}. Coincident with a strong reduction of fluctuations, the authors observed enhanced core confinement, leading to strong density peaking, a further rise in {beta}{sub p}, and a bootstrap current increasing to I{sub boot}/I{sub p} {approx} 0.8, peaked within the core. Ideal MHD calculations showed access to second stability during the density rise. During the enhanced performance phase core particle lifetime ({tau}{sub p}) and global energy lifetime ({tau}{sub E}) increased by factors of 2 and 1.2 respectively. Transport analysis showed that core particle and thermal diffusivities D{sub e} and {chi}{sub eff} approached neoclassical values. During the low current experiments, large losses of fast ions (typically {approximately}50% at 0.4 MA) were observed; at higher currents these losses are much smaller. The authors have also investigated discharges with current rampdown to high {beta}{sub p}. For a 5 to 6 {tau}{sub E} duration following rampdown, enhanced values of {beta}{sub p}, normalized toroidal beta ({beta}{sub N}), and {tau}{sub E} were obtained at high internal inductance ({ell}{sub i}). During both the ramp and the high confinement phases, fast ion losses were low ({approximately}10%). The loss then increased, correlated with an increase in the anisotropy ratio of perpendicular and parallel plasma pressure that suggests a fast ion loss mechanism coupled to the fast ion parallel energy.
Date: October 1, 1994
Creator: Stallard, B. W.; Casper, T. A. & Fenstermacher, M. E.
Partner: UNT Libraries Government Documents Department

Visible and Infrared Optical Design for the ITER Upper Ports

Description: This document contains the results of an optical design scoping study of visible-light and infrared optics for the ITER upper ports, performed by LLNL under contract for the US ITER Project Office. ITER is an international collaboration to build a large fusion energy tokamak with a goal of demonstrating net fusion power for pulses much longer than the energy confinement time. At the time of this report, six of the ITER upper ports are planned to each to contain a camera system for recording visible and infrared light, as well as other diagnostics. the performance specifications for the temporal and spatial resolution of this system are shown in the Section II, Functional Specifications. They acknowledge a debt to Y. Corre and co-authors of the CEA Cadarache report ''ITER wide-angle viewing and thermographic and visible system''. Several of the concepts used in this design are derived from that CEA report. The infrared spatial resolution for optics of this design is diffraction-limited by the size of the entrance aperture, at lower resolution than listed in the ITER diagnostic specifications. The size of the entrance aperture is a trade-off between spatial resolution, optics size in the port, and the location of relay optics. The signal-to-noise ratio allows operation at the specified time resolutions.
Date: March 1, 2007
Creator: Lasnier, C; Seppala, L; Morris, K; Groth, M; Fenstermacher, M; Allen, S et al.
Partner: UNT Libraries Government Documents Department

A Fast Visible Camera Divertor-Imaging Diagnostic on DIII-D

Description: In recent campaigns, the Photron Ultima SE fast framing camera has proven to be a powerful diagnostic when applied to imaging divertor phenomena on the National Spherical Torus Experiment (NSTX). Active areas of NSTX divertor research addressed with the fast camera include identification of types of EDGE Localized Modes (ELMs)[1], dust migration, impurity behavior and a number of phenomena related to turbulence. To compare such edge and divertor phenomena in low and high aspect ratio plasmas, a multi-institutional collaboration was developed for fast visible imaging on NSTX and DIII-D. More specifically, the collaboration was proposed to compare the NSTX small type V ELM regime [2] and the residual ELMs observed during Type I ELM suppression with external magnetic perturbations on DIII-D[3]. As part of the collaboration effort, the Photron camera was installed recently on DIII-D with a tangential view similar to the view implemented on NSTX, enabling a direct comparison between the two machines. The rapid implementation was facilitated by utilization of the existing optics that coupled the visible spectral output from the divertor vacuum ultraviolet UVTV system, which has a view similar to the view developed for the divertor tangential TV camera [4]. A remote controlled filter wheel was implemented, as was the radiation shield required for the DIII-D installation. The installation and initial operation of the camera are described in this paper, and the first images from the DIII-D divertor are presented.
Date: June 19, 2007
Creator: Roquemore, A; Maingi, R; Lasnier, C; Nishino, N; Evans, T; Fenstermacher, M et al.
Partner: UNT Libraries Government Documents Department

DIAGNOSIS OF EDGE LOCALIZED MODE EVOLUTION IN DIII-D USING FAST-GATED CID AND INFRARED CAMERAS

Description: The tangentially viewing visible and vertically viewing infrared cameras systems on DIII-D were upgraded to permit emission measurements during edge localized modes (ELMs) with integration times as short as 1 and 100 {micro}s respectively. The visible system was used to obtain 2-D poloidal profiles of CIII (465 nm) and D{sub {alpha}} (656.3 nm) emission with 20 {micro}s integration during various stages of ELM events in the lower DIII-D divertor. The infrared (IR) system was used to measure the heat flux to the divertor targets at 10 kHz with 100 {micro}s exposure. Upgrades to the data processing and storage systems permitted efficient comparison of the temporal evolution of these measurements.
Date: August 1, 2002
Creator: GROTH, M.; FENSTERMACHER, M.E.; LASNIER, C.J.; HERNANDEZ, R.; MOELLER, J.M. & STURZ, R.A.
Partner: UNT Libraries Government Documents Department