Doppler broadening

About: Doppler broadening is a research topic. Over the lifetime, 5509 publications have been published within this topic receiving 92552 citations.

Nonlinear dynamics of tearing modes in the reversed field pinch

Abstract: The results of investigations of nonlinear tearing‐mode dynamics in reversed field pinch plasmas are described. The linear instabilities have poloidal mode number m=1 and toroidal mode numbers 10≲n≲20, and the resonant surfaces are therefore in the plasma core. The nonlinear dynamics result in dual cascade processes. The first process is a rapid m=1 spectral broadening toward high n, with a simultaneous spreading of magnetic turbulence radially outward toward the field‐reversal surface. Global m=0 perturbations, which are driven to large amplitudes by the m=1 instabilities, in turn trigger the m=1 spectral broadening by back coupling to the higher n. The second process is a cascade toward large m and is mediated by m=2 modes. The m=2 perturbations have the structure of localized, driven current sheets and nonlinearly stabilize the m=1 modes by transferring m=1 energy to small‐scale dissipation. The calculated spectrum has many of the qualitative features observed in experiments.

A modeling study of the effect of drizzle on cloud optical depth and susceptibility

Abstract: This paper examines the impact of drop spectral broadening, generated by the collection process, on the optical depth, cloud albedo, and susceptibility of marine stratocumulus clouds. The results are arrived at using (1) the output from a simple box model calculation of collection and (2) the output from an eddy-resolving model of stratocumulus clouds that explicitly represents the size distribution of the drops. It is shown that commonly used relationships for cloud optical properties developed for narrow spectra do not generally apply to spectra undergoing spectral broadening. The optical depth dependence on the drop number concentration to the one-third power is shown to be an overestimate of the optical depth when spectra broaden through collection. In addition, the cloud susceptibility dependence on drop number is shown to be larger for spectra experiencing broadening than for narrow spectra.

Correlation Effects in the Two-Dimensional Vibrational Spectroscopy of Coupled Vibrations

Abstract: Correlated energy shifts in the spectral broadening of coupled vibrational transitions are shown to have clear signatures in infrared two-dimensional dispersed vibrational echo (DVE) spectroscopy. ...