Graduate School in Nonlinear Science

Sponsored by The Danish Research Agency

MIDIT                              OFD                          CATS
Modelling, Nonlinear Dynamics      Optics and Fluid Dynamics    Chaos and Turbulence Studies
and Irreversible Thermodynamics    Risø National Laboratory     Niels Bohr Institute and 
Technical University of Denmark    Building 128                 Department of Chemistry
Building 321                       P.O. Box 49                  University of Copenhagen 
DK-2800 Lyngby                     DK-4000 Roskilde             DK-2100 Copenhagen Ø
Denmark                            Denmark                      Denmark


by Thomas Sunn Pedersen
Columbia University

Thursday, March 15, 2001, 14.00 h
at OFD Meeting Room, Building 130, Risø National Laboratory

Abstract: A new basic plasma physics experiment, called the Columbia Non-neutral Torus (CNT) is being designed at Columbia University. In CNT, we will study pure electron plasmas in two fundamentally different toroidal magnetic geometries - a pure toroidal field, with closed field lines and no flux surfaces, and a stellarator configuration, which has nested closed flux surfaces even in the absence of plasma current. If successful, this will be the first pure electron plasma experiment in a stellarator geometry, and one of the first electron plasma experiments in a pure toroidal field. By starting out with a pure electron plasma and adding neutral gas, we may also be able to create a non-neutral electron-ion plasma, which would be strongly rotating. In recent years, fusion experiments have shown that strong rotation and shear can have a profound effect on plasma confinement, so there is significant interest in studying strongly rotating electron-ion plasmas. The stellarator geometry will be quasi-helical, which minimizes drift excursions, and hence, allows us to confine high energy particles at a relatively low magnetic field strength. This ability to confine energetic particles may allow us to efficiently trap positrons in the CNT device. We may also be able to conduct the first laboratory studies of confined positron-electron plasmas. In this presentation, we will describe the physics issues which we plan to address in CNT, and discuss the preliminary design of the experiment.