Conditions for Inception of Relativistic Runaway Discharges in Air

Abstract

Terrestrial gamma ray flashes (TGFs) (Fishman et al., 1994) represent a spectacular naturally occurring high energy phenomenon in the Earth's atmosphere. These events contain photons with several tens of mega electron-volt energies and likely involve large quantities of energetic electrons, sharing the same physical origin as X-rays generated by laboratory sparks (Stankevich & Kalinin, 1967) or originating from stepping lightning leaders (Moore et al., 2001). Dwyer et al. (2012) provide a review of principal physical processes and experimental findings on TGFs and related phenomena.It has been discovered by Dwyer (2003) that in order to explain observed intensities of TGFs a feedback mechanism should be involved in these events when an avalanche of relativistic electrons launches positrons and X-rays backwards at its origin to provide additional seeding and replenishment of the avalanche. Dwyer (2003) noted a physical analogy between this relativistic feedback mechanism and feedback mechanisms in conventional Townsend discharges involving positive ions and optical photons. The self-consistent modeling of a large scale streamer (domain size ∼5 km) and related space charge effects driven by the relativistic feedback discharges in air around 11-12 km altitudes have been reported by Dwyer (2012) and Liu and Dwyer (2013). It has been

On the Self‐Quenching of Relativistic Runaway Electron Avalanches Producing Terrestrial Gamma Ray Flashes

“…Their initial energy is 1 MeV. These seed electrons can be thought of as produced by cosmic ray secondaries (e.g., Chilingarian et al, 2021), thermal runaway electrons injected by a lightning leader (e.g., Celestin et al, 2015) or relativisticfeedback-produced electrons (e.g., Dwyer, 2003;Pasko et al, 2023). The injection rate is a variable parameter between the different simulations.…”

Remote Sensing of Source Currents of Narrow Bipolar Events Using Measured Electric Fields

“…Because of the short duration of NBEs, the assumed length of the discharge channel is several hundred meters or less (Watson & Marshall, 2007; Dwyer & Uman, 2014; Rison et al., 2016). It has been suggested recently that relativistic runaway discharges driven by photoelectric feedback can be sources of NBEs on these compact scales (Pasko et al., 2023). Significantly longer channel lengths were estimated in (Eack, 2004; da Silva & Pasko, 2015).…”

Optimal Conditions for the Generation of Runaway Electrons in High-Pressure Gases

“…In works [99,100], attention was focused on the study of RAEs in TOKAMAK-type installations and devices for their diagnostics in these conditions. Works [101][102][103][104][105] studied RAEs registered in atmospheric discharges, and work [106] investigated the application of RAE discharges for materials processing.…”