|icc_2006_hill.pdf||2006-02-23 11:12:30||David Hill|
Plans for Auxiliary Heating Experiments on SSPX
Author: David N. Hill
Submitted: 2005-12-21 16:02:03
Co-authors: T.A. Casper, H.S. McLean, J. Moller, L.D. Pearlstein, and R.D. Wood
Lawrence Livermore National Laboratory
7000 East Ave
Livermore, CA 94551-0
Recent results from the SSPX spheromak, in which peak electron temperatures Te ~350eV were obtained, provide strong motivation for adding auxiliary heating to study energy transport and pressure limits. At 300eV, 1.8MW of neutral beam injection (NBI) heating would match the ohmic heating in the core plasma to provide a known and controlled heat source for the first time in a spheromak. Neutral-beam heating will allow us to vary independently the heating power, plasma current, and confining field to study energy confinement scaling. In addition, the ability to increase the plasma pressure independent of the field will let us explore the physics of the beta limit. Looking further ahead, NBI will make possible deployment of beam-based core diagnostics such as charge-exchange recombination (for Ti, rotation, and Zeff), beam emission spectroscopy (for density fluctuations), and motional Stark Effect (for internal field measurements). Historically, the application of NBI to fusion devices of all types (e.g. tokamaks, stellarators, and most recently, reversed field pinches) has increased the quality and scientific output of experiments significantly.
The addition of NBI would follow by about a year the commissioning of a new modular solid-state programmable capacitor bank late in CY2006. We plan to procure the beams from the Budker Institute in Russia. Preliminary modeling using the CORSICA code points to a favorable outcome with realistic neutral beam heating pulses. Using beam parameters similar to those proposed here (1.5MW total power), the code predicts confined 25keV ion orbits in the core, a significant increase in core plasma pressure, and a rise in electron temperature from 200 to 380eV over 4msec. The expected confinement of fast ions in SSPX may provide a direct measure of the quality of magnetic fields in the driven spheromak.
This work performed under the auspices of the USDOE by LLNL under contract 7405-Eng-48.
E.B. Hooper (poster)