Excitation d'oscillations électroniques dans une onde de choc. Applications radioastronomiques

Space Charge Wave Amplification in a Shock Front and the Fine Structure of Solar Radio Noise

“…It is true that the Mott-Smith analysis does not apply to weak shocks. * Nevertheless, in the absence of any compelling reasons to suspect sharp discontinuities, the progressive decrease of the bandwidth of amplification .with the shock strength would presumably carry over into the region of weak shocks, and is, moreover, in agreement with the analysis of Denisse and Rocard (1951).…”

“…The roots of the dispersion equation indicate frequency oondwidths of space charge wave amplification that decrease with the shock strength. It is suggested, in agreement with Denisse and Rocard (1951), that the storm bursts of narrow bandwidth originating in shock fronts constitute the elementary fine-structure components of solar radio noise bursts. …”

“…We also neglect the small polarization effect (Denisse and Rocard 1951) and assume the electrons and ions to have a common mass velocity. On account of our neglect of the polarization effect, the concentration functions will refer indifferently to the ion or the electron.t…”

“…of the base frequency. Denisse and Rocard (1951) suggested the origin of these elementary storms to be the space charge wave amplification in a shock front. They drew attention to the fact that the electron velocity distribution in the shock front of an ionized gas will depart from the Maxwellian one, developing a secondary hump at a velocity exceeding the mean thermal motion of the electrons.…”