http://www.davidpace.com/physics/materi ... es-prl.htm
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The interesting result presented in this paper concerns the appearance of oscillations in the electron temperature of the plasma. The unique aspect of these oscillations is that they arise without us forcibly driving them, hence, the “spontaneous” part of the title. Our experiment consists of a narrow filament of hot plasma surrounded by a much larger and much colder plasma. This filament serves as a resonance cavity for the temperature oscillations. Resonance cavity, in this case, means that one-fourth of the wavelength of the thermal wave (i.e., the wave behind the temperature oscillations) fits inside the heated plasma filament. The entire situation is analogous to thermal waves that have been previously studied in solids, liquids, and gases.