Experimental Identification of the Kink Instability as a Poloidal Flux Amplification Mechanism for Coaxial Gun Spheromak Formation
The magnetohydrodynamic kink instability is observed and identified experimentally as a poloidal flux amplification mechanism for coaxial gun spheromak formation. Plasmas in this experiment fall into three distinct regimes which depend on the peak gun current to magnetic flux ratio, with (I) low values resulting in a straight plasma column with helical magnetic field, (II) intermediate values leading to kinking of the column axis, and (III) high values leading immediately to a detached plasma. Onset of column kinking agrees quantitatively with the Kruskal-Shafranov limit, and the kink acts as a dynamo which converts toroidal to poloidal flux. Regime II clearly leads to both poloidal flux amplification and the development of a spheromak configuration.
© 2003 The American Physical Society. Received 24 February 2003; published 30 May 2003. The authors acknowledge S. Pracko, C. Romero-Talamás, and D. Felt for technical assistance and H. Bindslev for asking about kink paramagnetism. This work was supported by U.S.-DOE Grant No. DE-FG03-98ER544561 and Fusion Energy Sciences Fellowship Program.
Published - HSUprl03.pdf
Accepted Version - 0304104.pdf