Measurements of ion wave turbulence by microwave scattering

Abstract

Ion wave turbulence spontaneously excited in a current-carrying plasma is investigated by the microwave scattering method. The dispersion relation, the wavenumber spectra, and the angular spectra of the ion wave turbulence are determined from the angular distribution of the scattered wave. The wavenumber spectrum has a peak around k ≃ νin/ vp, and decreases as k−4.8±0.5 with increasing k, where νin is the ion-neutral collision frequency and vp is the phase velocity of the ion wave. The angular spectrum of the wave energy is found to broaden as the total wave energy, W, increases along the electron drift. The effective collision frequency, νf, for electrons is also measured by the rf probe method as well as the dc method. An anomalous increase in νf is observed with the increase in W along the electron drift. The present experimental results are consistent with the theory of perturbed ion orbits.

Spectrum of turbulent ion acoustic waves in a magnetic field

“…Since the spectra presented in this paper are for a specific set of plasma parameters, a direct comparison with experimental results cannot be made. However, it may be noted that the shape of the ion acoustic frequency spectra measured by STESZEL (1978) and MOSTOVYCH and DESILVA (1984) in the laboratory, and by GURSETT and FRANK (1978) in the solar wind, are consistent with the one shown in Fig. 4.…”

“…The angular spectrum obtained by us (Fig. 3), has the same form as measured angular spectra (YAMADA and RAETHER, 1974;MASE and TSUKISHIMA, 1975). The energy is peaked along the direction of the electron drift.…”

“…The electric field fluctuation spectrum is one such characteristic that can be measured in the laboratory as well as in space plasmas. Ion acoustic spectra have been studied in the laboratory for unmagnetized plasmas (YAMADA and RAETHER, 1974;MASE and TSUKISHIMA, 1975;SLUSHER et ai., 1976SLUSHER et ai., ,1980STENZEL, 1978;KAWAI et al, 1978) as well as for magnetized plasmas (GEKELMAN and STENZEL, 1978). Also spectral measurements have been made in space plasmas (CURNETT el ai., 1978,1979).…”

Observation of asymmetric power spectra of density fluctuations in the JIPP T-IIU plasma by far-infrared laser scattering

“…Regarding the third feature, the broad spectral widths suggest that some non-linear processes such as mode coupling may take place in the plasma. These nonlinear processes could result in a modification of the linear dispersion relation, although the change is such that the frequency decreases in the case of ion acoustic turbulence [19]. However, the experimental results show a linear dispersion relation, as mentioned above.…”

Ion-acoustic solitary pulses in a dense plasma

“…Therefore, the study of plasma excitations in magnetized dense plasmas allow us learning different basic wave phenomena, such as solitons, shock waves, double layers, vortices, etc. One of the basic wave processes namely ion-acoustic (IA) waves in celestial as well as terrestrial plasma system have been studied for several decades both theoretically and experimentally [13,14,15,16,17,18,19,20,21]. Washimi and Taniuti [13] were the first to derive the Korteweg de-Vries (KdV) equation governing the propagation of IA waves in a collisionless plasma.…”