Doublet CT Studies at SSX-FRC
Abstract
We report the latest results of spheromak merging studies at SSX-FRC. Merging of two spheromaks with equal and opposite helicities generates an object with no net helicity. The object (which we call a doublet CT) has properties of spheromaks at the ends (toroidal and poloidal fields of comparable magnitudes) but with properties of an FRC in the midplane (purely poloidal field). Typical parameters are 3-4 mWb poloidal flux, 1 kG edge field, 10^15 cm-3 density, and s > 10. Detailed dynamics are measured with 128 simultaneous measurements of vector B for determination of global mode structure for n = 0, 1, 2. The doublet CT object is unstable to an n = 1 tilt mode but with a slower than MHD rate (6-8 axial MHD times). Recent 3D nonlinear resistive MHD numerical simulations have satisfactorily reproduced the large scale dynamics of the experiment for values of resistivity and viscosity consistent with experimental conditions. We have evidence of high velocity flows from Mach probe studies and of electron heating from a soft x-ray array (both at the midplane). Flow measurements from a new ion doppler spectroscopy diagnostic will be presented if available.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- November 2004
- Bibcode:
- 2004APS..DPPHP1058B