Laboratory modeling of magnetospheric ion conics

Ion conics are generated in a laboratory plasma using methods consistent with natural phenomena in the earth's magnetosphere-ionosphere system. A plasma volume is subjected to either local or nonlocal electrostatic turbulence which in turn is responsible for accelerating the ions transverse to the confining magnetic field. The ions flow away from the source of turbulence in a spatially decreasing magnetic field where the {dollar}munabla B{dollar} force and magnetic-moment conservation work to distort the heated distribution. Laser-induced-fluorescence (LIF) signals, measured downstream from the plasma source with the aid of optical tomography techniques, reveal substantial ion heating and conic formation. A variety of conic structures was observed, in particular the "ion bowl" distribution. The structure of the conics may be interpreted readily in terms of the magnetic field ratio from source to optical detection site, the applied external power, and the penetration of the wave downstream from the RF source.; Because the optical detection site was in a region of very low ion density and magnetic field, and because several measurements over a short time period were required in order to retrieve a useful data set, it was necessary to re-develop the optical tomography system to accommodate this research project. The original device has been replaced by an improved model which is less perturbing to the plasma, and can be used under much wider variations of plasma density and external magnetic field than the first-generation device. Automation of the scan-collection process enables a complete distribution to be obtained in less than five minutes, thereby freeing the user to focus on other aspects of the research. Techniques are discussed which show how one may identify anomalous velocity distributions by examining only a single velocity scan.