Scaling studies in field reversal experiments

The stable period of field-reversed configurations, defined by the onset of the rotational n = 2 instability, is observed to scale with R2/ ρi over a new, wider range of experimental conditions, where R is the major radius and ρi is the ion gyro-radius indexed to the external field. The scaling factor is approximately 6.0×10−7 sec cm−1 over a range of R2/ ρi from 18 to ∼100 cm in which 1/ ρi varied from 1 to 5 cm−1 and R varied by approximately 30%. In a complimentary study, the stable period was observed to be independent of Ti over a range of 200–1200 eV when R2/ ρi was held approximately constant. The theoretical correlation of the stable period with the particle containment time, and hence with R2/ ρi, are discussed.