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Title: Reduction of Carbon Influx by Minimizing Title Heating DIII-D

Abstract

No abstract prepared.

Authors:
; ; ;
Publication Date:
Research Org.:
General Atomics, San Diego, CA (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
766645
Report Number(s):
GA-A23277
TRN: US0200995
DOE Contract Number:
AC03-99ER54463
Resource Type:
Conference
Resource Relation:
Conference: 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, NM (US), 10/25/1999--10/29/1999; Other Information: PBD: 1 Nov 1999
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CARBON; DOUBLET-3 DEVICE; MITIGATION; TEMPERATURE CONTROL

Citation Formats

Friend, M.E., Baxi, C.B., Mahdavi, M.A., and O'Neill, R.C.. Reduction of Carbon Influx by Minimizing Title Heating DIII-D. United States: N. p., 1999. Web.
Friend, M.E., Baxi, C.B., Mahdavi, M.A., & O'Neill, R.C.. Reduction of Carbon Influx by Minimizing Title Heating DIII-D. United States.
Friend, M.E., Baxi, C.B., Mahdavi, M.A., and O'Neill, R.C.. 1999. "Reduction of Carbon Influx by Minimizing Title Heating DIII-D". United States. doi:. https://www.osti.gov/servlets/purl/766645.
@article{osti_766645,
title = {Reduction of Carbon Influx by Minimizing Title Heating DIII-D},
author = {Friend, M.E. and Baxi, C.B. and Mahdavi, M.A. and O'Neill, R.C.},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1999,
month =
}

Conference:
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  • 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 puffingmore » 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.« less
  • To minimize the amounts of coal used and CO[sub 2] exhausted in an iron bath smelting reduction process, conditions for effective use of volatile matter (VM) in the pre-reduction of iron oxide were examined; 1 kg coal having 36.5 mass% VM was carbonized under rising temperature conditions up to a maximum temperature ranging from 873 to 1,273 K and 2 kg iron oxide pellets packed in a separate reactor were reduced with this gas except tar at a constant temperature equal to the maximum carbonization temperature (called here processing temperature t[sub P]). The results are (1) In the cases ofmore » T[sub P][equals]873 and 973 K, VM does not release enough, but in the cases of T[sub P][equals]1,073 K and more, VM releases up to about the amount of proximate analysis: (2) Hydrocarbons are considered to decompose into hydrogen and carbon or carbon monoxide through cracking or reforming reactions in the reduction reactor at higher temperatures and to contribute to the reduction reactions: (3) Fractional reduction F increases linearly with T[sub P] as F[equals]0.00091T[sub P]-0.73: (4) As T[sub P] rises, contribution of hydrogen to the reduction reactions increases from 40% to 60%.« less
  • Various approaches are available for minimizing the generation of waste in a process system. They include source reduction, recycling, waste separation, waste concentration, and waste exchange at the highest level of U.S. EPA`s waste reduction hierarchy. All of these approaches, however, depend primarily on the structure of the process. For instance, various processes may need different waste treatment systems even if they generate the same product. Similarly, the risk depends on the structure of the process. Thus, the design of facilities for waste minimization and risk reduction can not be isolated from that of the process for product generation asmore » often done conventionally. All the steps of process design and waste minimization and risk reduction should be integrated into one consistent method. The integration, however, renders the already complex tasks involved in process synthesis exceedingly cumbersome. A highly efficient and mathematically rigorous technique is indeed required to overcome this difficulty. The present work aims at establishing such a technique.« less
  • Reduced recycling, reduced edge neutral pressure, improved density control, and improved discharge reproducibility have been achieved in the DIII-D tokamak by in situ helium conditioning of the graphite tiles. An improvement in energy confinement has been observed in hydrogen discharges with hydrogen beam injection after helium preconditioning. After the graphite wall coverage in DIII-D was increased to 40%, helium glow wall conditioning, routinely applied before each tokamak discharge, has been necessary to reduce recycling and obtain H-mode. The utilization of helium glow wall conditioning was an important factor in the achievement of an ohmic H-mode, i.e. no auxillary heating, withmore » significant improvement in ohmic energy confinement. 16 refs., 8 figs.« less
  • The application of fast wave power in DIII-D has proven effective for both electron heating and current drive. Since the last RIF Conference FW power has been applied to advanced confinement regimes in DIII-D; negative central shear (NCS), VH- and H-modes, high {beta}{sub p}, and high-{ell}i. Typically these regimes show enhanced confinement of toroidal momentum exhibited by increased toroidal rotation velocity. Indeed, layers of large shear in toroidal velocity are associated with transport barriers. A rather common occurrence in these experiments is that the toroidal rotation velocity is decreased when the FW power is turned on, to lowest order independentmore » of whether the antennas are phased for co or counter current drive. At present all the data is for co-injected beams. The central toroidal rotation can be reduced to 1/2 of the non-FW level. Here the authors describe the effect in NCS discharges with co-beam injection.« less