view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Radio wave generation by multistream charge interaction. Sen, Hari K. ; Feinstein, J. Abstract The excitation of plasma oscillations in traveling beams is reviewed; analytic and graphical methods are employed to ascertain the ranges of parameters over which wave growth may exist, and to determine contours of constant amplification factor. The effect of thermal velocities is taken into account by utilizing approximations to a Maxwellian distribution. The magnitude of the wave growth is found to be sufficiently large to produce a saturated equilibrium within a few meters or less. Only a small amount of energy conversion is obtained, however, under highly mismatched conditions. It is found that the possibility of growth exists even for beam injection velocities much smaller than the mean thermal motion in the region: Narrow band widths are encountered under these circumstances, of the order obtained experimentally for many of the smaller bursts of solar radio noise. For beam injection velocities larger than the local mean thermal motion, a truncation appears in the curves, indicating the possibility of bursts at separated frequencies with no activity at intermediate frequencses. An investigation of the effect of ~he initiating disturbance upon the frequency band generated leads to the conclusion that where the possibility of growth in time exists, a spatial description of initial conditions gives rise to a broader band than does a temporal prescription. Previously suggested mechanisms for the conversion of the longitudinal plasma oscillations in to transverse electromagnetic energy, e.g., presence of transverse static magnetic field or transverse mass velocity, are considered quantitatively, and found to be inadequate. A more promising mechanism is suggested, viz., the occurrence of physical conditions which require, for a net energy delivery, only a matching either in frequency or in wave length between the longitudinal space charge wave and the transverse eiectromagnetic oscillations. Such a situation can arise if steep gradients are present in the medium characteristics, as might occur near the edges of prominence eruptions, or in a rapidly growing wave. A quantitative investigation of energy transfer under these conditions requires a non-linear theory, which is beyond the scope of the present paper. Harvard College Observatory, Cambridge, Mass. and National Bureau of Stjndards, Washington, D. C. Publication: The Astronomical Journal Pub Date: April 1951 DOI: 10.1086/106587 Bibcode: 1951AJ.....56Q..48S full text sources ADS |