A laboratory investigation of the high‐frequency Farley‐Buneman instability

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Abstract
A laboratory investigation of the high‐frequency Farley‐Buneman instability is described. The instability was studied theoretically by Lee et al. (1971) and is predicted to occur in the low E region of the ionosphere when the E/B drift velocity of the electrons relative to the ions is several times Cs, the ion acoustic speed. In our experiments an increase of the electric field well above the Lee et al. “threshold” merely enhances the general power level of the fluctuations but does not affect appreciably their spectral shape. The observed frequency spectra fall off very rapidly with increasing frequency, with a spectral shape of the type P(f) ∝ f−3.5. This result agrees well with recent ionospheric observations and suggests that a recently proposed mechanism of anomalous wave electron heating in the lower E region should not be linked to the presence of short‐wavelength (10–30 cm) irregularities.