ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
Examination is made of the relation between the distribution function of the ions confined in a tandem mirror and the current–voltage (I–V) characteristics of the end loss ions collected on a gridded energy analyzer. To do this, a model ion distribution function characterized by two parameters, an anisotropy parameter χ and a decay parameter Y is used. The decay parameter represents depletion of ion distribution in the loss cone. A Maxwellian distribution as the limit of Y=∞ is shown not to reproduce the measured I–V curve as an energy spectrum of the ions lost from the central cell of the GAMMA 10 tandem mirror [Phys. Rev. Lett. 55, 939 (1985)]. The ions in the central cell are subject to strong ICRH and have a highly anisotropic velocity distribution. These ions are deeply trapped in the central cell and the loss cone is not fully occupied. The model distribution with a small value of Y represents such features of the ion distribution. From comparison between a measured loss current and calculated one, the decay parameter of the model distribution function is roughly determined. The model distribution with this parameter yields I–V characteristics similar to the measured one. The present article gives the relation between the apparent ion temperature Ti simply determined from the slope of the log plot of the measured I–V curve and the real parallel ion temperature Ti(parallel). When the ion distribution is of a loss cone type, Ti is almost equal to Ti(parallel). On the other hand, Ti can be more than two times as high as Ti(parallel) if the ion distribution is Maxwellian-like. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1147038
Permalink
