Ivan Soares Ferreira | Searcharxiv

arXiv2021

Generation possibility of gamma-ray glows induced by photonuclear reactions

Relativistic runaway electron avalanches (RREAs) imply a large multiplication of high energy electrons (~1 MeV). Two factors are necessary for this phenomenon: a high electric field sustained over a large distance and an energetic particle to serve as a seed. The former sustains particle energies as they keep colliding and lose energy randomly, and the latter serves as a multiplication starting point that promotes avalanches. RREA is usually connected to both terrestrial gamma-ray flashes (TGFs) and gamma-ray glows (also known as Thunderstorm Ground Enhancement (TGE) when detected at ground level) as possible generation mechanism of both events, but the current knowledge does not provide a clear relationship between these events (TGF and TGE), beyond their possible common source mechanism, still as they have different characteristics. In particular, their timescales differ by several orders of magnitude. This work shows that chain reactions by TGF byproducts can continue for the timescale of gamma-ray glows and even provide energetic particles as seeds for RREAs of gamma-ray glows.

physics.ao-ph↗

arXiv2004

Plasma Diagnostic and Performance of a Permanent Magnet Hall Thruster

Electric propulsion is now a sucessfull method for primary propulsion of deep space long duration missions and for geosyncronous satellite attitude control. Closed Drift Plasma Thruster, so called Hall Thruster or SPT (stationary plasma thruster) were primarily conceived in USSR (the ancient Soviet Union) and now it is been developed by space agencies, space research institutes and industries in several countries such as France, USA, Israel, Russian Federation and Brazil. In this work, we show plasma characteristics and performance of a Hall Thruster designed with an innovative concept which uses an array of permanent magnets, instead of an eletromagnet, to produce a radial magnetic field inside its cylindrical plasma drift channel. Within this new concept, we expect to develop a Hall Thruster within power consuption that will scale up to small and medium size satellites. A plasma density and temperature space profiles inside and outside the thruster channel will be shown. Space plasma potential, ion temperature measurements based on doppler broadenning of spectral lines and ion energy measurements are shown for different plasma production regimes. Experimentaly measured propulsion and power consumption will also be shown and compared with computational simulation models using the same plasma experimental conditions. In both cases the results are showing a thrust range between 40mN to 80mN which is close to the thrust levels obtained with a commercial SPT 100 using 30% less electrical power.

physics.plasm-ph↗