The effect of direct positron production on relativistic feedback rates
Abstract
Relativistic feedback produces a self-sustaining runaway electron discharge via the production of backward propagating positrons and back-scattered x-rays. To date, only positrons created from pair-production by gamma-rays interacting with the air have been considered. In contrast, direct pair-production involves the creation of electron-positron pairs directly from the interaction of energetic runaway electrons with nuclei, and so it does not require the generation of bremsstrahlung gamma-rays. For high electric fields, where the runaway electron avalanche length scales are short, pair-production involving bremsstrahlung gamma-rays makes a smaller contribution to the total relativistic feedback rates than at lower fields, since both the bremsstrahlung interaction and the pair-production need to occur over a short length. On the other hand, for high fields, because direct positron production only involves one interaction, it may make a significant contribution to relativistic feedback rates in some cases. In this poster, we shall present the direct positron production cross-sections and calculate the effects on the relativistic feedback rates due to this process.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMAE23A0407V
- Keywords:
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- 3324 ATMOSPHERIC PROCESSES Lightning;
- 3304 ATMOSPHERIC PROCESSES Atmospheric electricity;
- 3359 ATMOSPHERIC PROCESSES Radiative processes