Divertor Research On The Diii D Tokamak

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ISBN 13 :
Total Pages : 18 pages
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Download or read book Collaboration on DIII-D Five Year Plan written by and published by . This book was released on 2003 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document summarizes Lawrence Livermore National Laboratory's (LLNL) plan for fusion research on the DIII-D Tokamak, located at General Atomics (GA) in San Diego, California, in the time period FY04-FY08. This document is a companion document to the DIII-D Five-Year Program Plan; which hereafter will be referred to as the ''D3DPP''. The LLNL Collaboration on DIII-D is a task-driven program in which we bring to bear the full range of expertise needed to complete specific goals of plasma science research on the DIII-D facility. This document specifies our plasma performance and physics understanding goals and gives detailed plans to achieve those goals in terms of experimental leadership, code development and analysis, and diagnostic development. Our program is designed to be consistent with the long-term mission of the DIII-D program as documented in the D3DPP. The overall DIII-D Program mission is ''to establish the scientific basis for the optimization of the tokamak approach to fusion energy production''. LLNL Magnetic Fusion Energy (MFE) supports this mission, and we contribute to two areas of the DIII-D program: divertor physics and advanced tokamak (AT) physics. We lead or contribute to the whole cycle of research: experimental planning, diagnostic development, execution of experiments, and detailed analysis. We plan to continue this style in the next five years. DIII-D has identified three major research themes: AT physics, confinement physics, and mass transport. The LLNL program is part of the AT theme: measurement of the plasma current profile, and the mass transport theme: measurement and modeling of plasma flow. In the AT area, we have focused on the measurement and modeling of the current profile in Advanced Tokamak plasmas. The current profile, and it's effect on MHD stability of the high-[beta] ''AT'' plasma are at the heart of the DIII-D program. LLNL has played a key role in the development of the Motional Stark Effect (MSE) diagnostic. Starting with a single channel, the system has grown to 40 channels with three separate systems. We have continually developed new calibration techniques, with a goal of accuracy in the magnetic field pitch angle measurements of ≈0.1 degree. Measurements of the radial electric field E{sub r} have also been achieved. In the next five year period, GA plans on rotating one of the neutral beams so that it injects opposite to the sense of the plasma current (counter-injection). This enables two orthogonal MSE views of the neutral beam so that J(r) and E{sub r} can be obtained directly. In addition, the new views can be optimized so that increased spatial resolution will be obtained. Our plan is to install these new systems when the neutral beam is reoriented, and continue to provide high-resolution, ''state of the art'' current profile measurements for the DIII-D AT program. In the divertor physics area, our goal is the development of a model of the scrapeoff layer (SOL) and divertor plasmas which is benchmarked with data. We have identified the need for measurements of SOL flow and ion temperature. Working with GA, we are proposing a new edge Charge Exchange Recombination (CER) diagnostic. The understanding of SOL flow is important for understanding the tritium inventory problem in ITER. In addition, using plasma flow to ''entrain'' impurities in the divertor region (enabling a low density radiative divertor) is the current AT divertor heat flux control scenario. We are also augmenting our edge modeling capabilities with a coupled UEDGE (fluid code) with the BOUT (edge turbulence) code. Further work, funded through LLNL theory, is planned to develop a kinetic treatment of the edge. All of these efforts contribute to the understanding of the edge pedestal in the tokamak, an important AT and ITER topic. A secondary goal is the understanding of Edge Localized Modes (ELMs), which are also important in the ITER design, as the repetitive bursts of heat flux can cause increased erosion and damage to the divertor plates. The modeling effort, particularly the kinetic treatment of the pedestal region described above, is aimed at an understanding of the pedestal plasma. We plan to add fast data acquisition to several of the DIII-D edge and SOL diagnostics, e.g. the filterscopes, and imaging spectroscopic cameras, so that we can study the fast time evolution of ELMs.