Plasma Science: From Fundamental Research to Technological Applications (1995)
Chapter: Laboratory Experiments
geomagnetic, and other instruments provide an important view of external plasma processes, and data acquired simultaneously from many sites provide a basis for understanding many different manifestations of magnetospheric and ionospheric dynamics that are closely linked to the solar wind. Recommendations from the scientific community include increasing the number of operating stations, as well as modernizing them, to enable development of precise and high-quality databases.
Lack of observations from the Southern Hemisphere, particularly digital data, is a serious problem. These data are necessary to understand the asymmetries that arise from summer-winter differences in the polar ionospheres and from asymmetries in the geomagnetic field itself. Digital data acquisition in the Antarctic is particularly important, and the Antarctic is the only region where stable instrument platforms can be easily placed at very high polar latitudes (in the polar cap).
Equal emphasis must be given to global arrays and to dense regional arrays of instruments. Concern should be paid to including complementary instruments within arrays in order to achieve a rich source of fundamental parameters. Arrays must also be utilized to deconvolve the spatial and temporal aliasing of the data. This is a particular problem with the interpretation of data from a single station or spacecraft. Thus, the coordinated use of multiple stations and multiple instruments should become increasingly the norm in data analysis.
Laboratory Experiments
When a phenomenon has been identified by a spacecraft and the basic physics of it is not well understood, the laboratory is the ideal place to study it. The problems encountered in space observations of single-point measurements and nonrepeatability are overcome in the lab. A well-planned experiment can be carefully tailored so that it is repetitive in space and time. Plasma laboratory technology has advanced to the point that many experiments pertinent to space plasma phenomena can be performed. For example, in wave studies, waves can be made linear or nonlinear by the turn of an amplifier knob. Furthermore, these waves can be launched from one or more antennas and their fields mapped in the near and far zone. Beams can be introduced from localized sources, density nonuniformities can be repeatably produced, impurities can be added in known amounts at a given location, and plasma drifts can be created. Furthermore, measurements can be acquired at thousands of three-dimensional spatial positions and thousands of time steps during the interaction. This is impossible in space. Laboratory experiments can address both local and global physics issues (the latter are often determined by boundaries). In some cases, one can comprehensively analyze physical phenomena simultaneously from both global and local points of view. Furthermore, experimental devices may be rapidly configured to perform new experiments as ideas are developed. This can happen on
