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.

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VLF hiss is proposed to result from convective beam amplification of incoherent Cerenkov whistler radiation by the beam of precipitating auroral electrons. The beam amplification mechanism is investigated by using the lowest‐order WKB wave kinetic equation and linear growth rates. It is shown that incoherent Cerenkov radiation cannot produce strong VLF hiss without beam amplification and that the beam amplification mechanism can account for the observed bandwidth and power fluxes of strong VLF hiss when the electron gyrofrequency is less than the electron plasma frequency. The theory is not adequate for high frequencies when the electron plasma frequency is less than the electron gyrofrequency, because nonlinear processes are important for frequencies near the plasma frequency.

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