SciTech Connect

Title: The Spheromak path to fusion energy

The Spheromak path to fusion energy The spheromak is a simple and robust magnetofluid configuration with several attractive reactor attributes including compact geometry, no material center post, high engineering {beta}, and sustained steady state operation through helicity injection. Spheromak physics was extensively studied in the US program and abroad (especially Japan) in the 1980` s with work continuing into the 1990s in Japan and the UK. Scientific results included demonstration of self-organization at constant helicity, control of the tilt and shift modes by shaped flux conservers, elucidation of the role of magnetic reconnection in the magnetic dynamo, and sustainment of a spheromak by helicity injection. Several groups attained electron temperatures above 100 eV in decaying plasmas, with CTX reaching 400 eV. This experiment had high magnetic field (>l T on the edge and {approximately} 3 T near the symmetry axis) and good confinement. More recently, analysis of CTX found the energy confinement in the plasma core to be consistent with Rechester-Rosenbluth transport in a fluctuating magnetic field, potentially scaling to good confinement at higher electron temperatures. The SPHEX group developed an understanding of the dynamo in sustained spheromaks but in a relatively cold device. These and other physics results provide a foundation for a new ``concept more » exploration`` experiment to study the physics of a hot, sustained spheromak. If successful, this work leads to a next generation, proof-of-principle program. The new SSPX experiment will address the physics of a large-scale sustained spheromak in a national laboratory (LLNL) setting. The key issue in near term spheromak research will be to explore the possibly deleterious effects of sustainment on confinement. Other important issues include exploring the {beta} scaling of confinement, scaling with Lundquist number S, and determining the need for active current-profile control. Collaborators from universities and other national laboratories are contributing experience from previous work, diagnostics, and physics support. Experiments at PPPL and Swarthmore are being conducted on the physics of magnetic reconnection, yielding physics results which should help advance the confinement work. A spheromak reactor will require steady state operation with the equilibrium fully supported by external coils. Although the present generation of experiments can provide data on the initial stages of the transition from short-pulsed operation, sustainment longer than the wall resistance time will be addressed in the proof-of-principle experiments. « less
Authors:
Publication Date:
OSTI Identifier:304511
Report Number(s):UCRL-ID--130429
ON: DE98058721; BR: YN0100000; TRN: 99:002181
DOE Contract Number:W-7405-ENG-48
Resource Type:Technical Report
Data Type:
Resource Relation:Other Information: PBD: 1 Apr 1998
Research Org:Lawrence Livermore National Lab., CA (United States)
Sponsoring Org:USDOE, Washington, DC (United States)
Country of Publication:United States
Language:English
Subject: 70 PLASMA PHYSICS AND FUSION; SPHEROMAK DEVICES; RESEARCH PROGRAMS; PLASMA CONFINEMENT; PLASMA DIAGNOSTICS; BETA RATIO; MHD EQUILIBRIUM