Anomalous cross-field transport in a Hall thruster inferred from direct measurement of instability growth rates.

The contribution of the electron drift instability to anomalous electron transport is experimentally assessed in a Hall effect discharge. The transport is represented by an anomalous collision frequency, which is related through quasilinear theory to the energy and growth rate of the instability. The wave energy is measured directly with ion saturation probes, while estimates of the growth rate are employed based on both linearized theory and direct measurement.

Growth and Saturation of the Electron Drift Instability in a Crossed Field Plasma.

The linear growth and nonlinear energy transfer of the electron drift instability (EDI) are experimentally measured in the plume of a low-temperature, Hall effect discharge. A frequency-based bispectral analysis technique applied to fast ion density fluctuation measurements shows a growth rate function that is qualitatively similar to predictions from the linear instability dispersion relation, but an order of magnitude smaller. Calculation of the nonlinear transfer function indicates multiple three-wave interactions between high-frequency resonances of the instability in addition to an inverse energy cascade toward lower-frequency modes.

The glass is half empty: Negative self-appraisal bias and attenuated neural response to positive self-judgment in adolescence.

Substantial changes in cognitive-affective self-referential processing occur during adolescence. We studied the behavioral and ERP correlates of self-evaluation in healthy male and female adolescents aged 12-17 ( = 109). Participants completed assessments of depression symptoms and puberty as well as a self-referential encoding task while 128-channel high-density EEG data were collected.

Adolescent positive self, negative self: associated but dissociable?

Adolescence is a period of significant identity development and particular vulnerability to depression associated with negative self-evaluation. We investigated if increased depressive symptom severity was also associated with positive self-evaluation. We also considered pubertal developmental differences in positive and negative self-evaluation, and if these could reflect dissociated facets of the self.