Comparison of TMX tandem mirror confinement with single-mirror experiments

Abstract

A hundredfold improvement is observed in the electron energy confinement time and the central-cell ion confinement time of the TMX tandem mirror relative to previous single-mirror experiments. A comparison of nine different single-mirror confinement experiments shows that the ion particle confinement increases with mean ion energy in several machines over a broad range of plasma parameters and plasma production methods.

Comment on a paper concerning the enhancement of irradiation-induced creep of metals by pulsed irradiation

“…However, with the correct value of 1.09 eV, such an enhancement should not be observable in stainless steels or nickel in agreement with experiments [2,3] …”

“…Such effects have fei ned the only seeming proof of enhanced irradiation creep during cyclic irradiation /$] as demonstrated in Ref. [2]. If temperature excursions due to switching the beam on or off are carefully avoided, no enhancement of irradiation creep could be detected in a wide range of pulsing frequencies and temperatures [ 31.…”

“…1 is a graphic representation of equation (1) using pN' and D,, values typical for austenitic stainless steels. In the same graph K,,, is included on the right hand ordinate by relating its scale to the frequency scale via equation (2). Although v and K are of course independent parameters in fusion devices, their anticipated ranges for tokamaks are such, that these can (by chance) also be included in the diagram: Fig.…”

The magnetic mirror approach to fusion

“…Also, there have been repeated comparisons, with greater or lesser quantitative accuracy, between F-P calculations of classical mirror losses and experimental observations. Figure 77, taken from an article by Simonen [316] shows (right side) a comparison of historical confinement data in conventional mirror systems with F-P predictions. Also shown are data points and projections for such systems.…”

The highest energy confinement measured on TMX-U

“…These are the highest values measured and do not represent typical observed values [1,2,7]. In the TMX-U standard tandem mirror operating mode, the global energy confinement product, nr| = 2 X 10 l0 cm~3-s, is twice as high as that achieved in TMX [13,14]. This increase may be attributed to improved vacuum conditions and improved microstability.…”