The large plasma research device (LAPD), a large, linear plasma research device designed to study space plasma processes, has been constructed at UCLA over the past four years. The LAPD has a 0.5×0.5 m2 oxide-coated cathode as a source which produces a 10-m-long plasma column with densities up to the mid 1012/cm3 range. The linear machine is surrounded by a set of 68 magnet coils which can generate an axial magnetic field of up to 3000 G. The vacuum chamber has 128 radial ports to ensure excellent access for probes and antennas. An internal probe drive capable of moving a set of probes to any position within the plasma column is described in a companion paper. This machine is a scientific instrument in its own right and was designed to be versatile enough to study a large variety of phenomena. The techniques employed in the design and construction are sufficiently useful to be discussed here so that others can benefit from our experience.

Whistler waves are launched toward a field‐aligned density striation in a laboratory plasma. Characteristic scale length and frequency ratios are scaled to closely reproduce situations found in the auroral ionosphere. Detailed measurements show that at the striation edge nearest the wave‐launching antenna, besides a reflected and a transmitted whistler wave, lower hybrid waves are also stimulated on both sides of the striation boundary in a manner consistent with the linear mode‐conversion model. We find that the energy density of the mode‐converted lower hybrid waves is typically 10% of the incident whistler wave energy density, reaching a maximum of 30% in one region. Lower hybrid waves are confined to within 2–3 perpendicular wavelengths in the interaction zone. Our results show that the interaction of electromagnetic whistler mode waves with density striations can cause significant amounts of energy to be deposited in the largely electrostatic lower hybrid mode and that it may therefore be a significant generation mechanism for these waves in certain regions of the ionosphere.

Energy densities are computed for geomagnetic field fluctuations in the Pc 3–4 range using H component magnetometer data recorded at South Pole station over a three‐month period from June 3 to September 4, 1982. Hourly values of the energy densities in the Pc 3 and Pc 4 period bands are found to be highly correlated during geomagnetic local daytime hours. The results of multivariate analyses between geomagnetic energies and upstream solar wind quantities show that the most important quantity in controlling the magnitude of the field fluctuations is the solar wind speed, with the IMF Bz component being of next importance. We conclude that the Kelvin‐Helmholtz instability at the dayside magnetopause is, statistically, the dominant energy source that contributes to ULF hydromagnetic wave activity at cusp latitudes.

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The transmission of fast magnetoacoustic waves generated in the solar wind to the dayside low latitudes deep in the magnetosphere is of vital importance in understanding the physics of some important aspects of the solar wind‐terrestrial interaction. This study provides two examples of such a transmission. Magnetospheric hydromagnetic energies are computed at hourly intervals for four period bands in the Pc 3–5 range (15–30, 30–60, 60–120, and 120–240 s). We use the horizontal component of magnetometer data recorded at AT&T Bell Laboratories and Air Force Geophysics Laboratory stations near L = 2 and L = 3 during January 27–30, 1979, an interval of moderate geomagnetic activity. High correlations are observed between the dayside ground‐based observations of the hourly magnetic energies in the Pc 3 frequency range and the direction of the interplanetary magnetic field. Linear regression and multivariate analysis techniques have been adopted. The statistical results support theories of magnetohydrodynamic wave generation in the solar wind (upstream from the bow shock) and the subsequent wave transmission through the bow shock, magnetosheath, and magnetopause. This leads to the observation of enhancements in Pc 3 at the low‐latitude terrestrial surface. In addition, we also carry out dynamic power spectral analyses of the ground data. These reveal several sudden enhancements in power for variations with periods in the range 15–50 s. At the time of two of these events occurring near local noon we observe large increases of compressional wave power in the solar wind. We take these two events to be specific examples of magnetoacoustic wave transmission of the type indicated by the statistical results.