The proton flux influence on electrical characteristics of a dual-channel hemt based on GaAs

The results of the simulation the influence of the proton flux on the electrical characteristics of the device structure of dual-channel high electron mobility field effect transistor based on GaAs are presented. The dependences of the drain current ID and cut-off voltage on the fluence value and proton energy, as well as on the ambient temperature are shown.

CONNECTION OF THE INTENSITY OF THE FLUX OF SCR PROTONS WITH THE VELOCITY OF THE CME AND WITH THE FADING OF THE RADIO EMISSION OF THE SUN IN THE DECAMETER RANGE

The relationship between SCR and CME and with fading of the continuum of noise storms and typeIV radio bursts in the decameter range is investigated. It was shown earlier that about 60% of CMEs associated with solar proton events are accompanied by deep fading of the solar radio emission in the decameter range, which coin-cides in time with CME registration. It has also been shown that fading is characterized by fading depth, the frequency bandwidth in which the fading occurs, as well as the duration of the fading and the frequency at which the maximum fading depth is observed. Further detailed studies have shown that for proton events accompanied by fading of the solar radio emission in the decameter range, the relationship between the intensity of the SCR proton flux and the CME velocity is much worse than for events without fading of the solar radio emission in the decameter range. However, it was foundthat for such events, the relationship between the flux of SCR protons and the CME velocity significantly increases if we take into account the fading depth of the solar radio emission in the decameter range.Earlier in (Isaeva, 2019), the results of a study of the relationship between the intensity of fading of the continuum of noise storms with the parameters of X-ray bursts, with the CME velocity and the velocity of coronal shock waves, as well as with the intensity of the SCR proton flux were presented. This paper presents the results of studying the relationship between the intensity of the SCR proton flux withthe parameters of type II and IV radio bursts, as well as with the CME velocity and with the velocity of coronal shock waves, depending on the intensity of fading of the solar radio emission in the decameter range at a frequency of 27 MHz. The frequency of 27 MHz was chosen because in the region of this frequency the maximum fading depth of the solar radio emission in the decameter range is observed.

Tuning Local Proton Flux in Yolk-Shell Cu@Cu2Se Nanoreactors to Enable Efficient Electrochemical Nitrate-Ammonia Conversion

Electrochemical nitrate (NO3−) reduction reaction (NO3−RR) represents an ideal alternative for ammonia (NH3) generation. Despite recent success on the synthesis of Cu-based electrocatalysts, the kinetics of Cu-catalyzed NO3−RR is still greatly limited by the slow proton transfer rate since the large energy barrier for water dissociation. Here, we report the construction of a yolk-shell structure, comprising a Cu core and Cu2Se shell that functions like the tandem nanoreactor. Specific, the Cu2Se shell with strong water dissociation ability can easily produce protons and then transfer to the Cu core for driving the reduction of NO3−. Intriguingly, the proton flux arriving to the Cu core can be well tuned by altering the void size of the yolk-structure, thereby enabling rapid proton transfer yet hindering the competitive hydrogen evolution. More importantly, operando Raman spectra reveal that the rapid proton transfer significantly promotes the hydrogenation of key intermediates for reducing the overall energy barrier of the NO3−RR. Consequently, the optimized yolk-shell structure enables highly selective and efficient NO3−RR with a large NH3 yield rate of 0.94 mmol cm−2 h−1. This work offers a fresh concept to boost the NO3−RR by tuning proton transfer rate.

OMEP-EOR: A MeV proton flux specification model for Electric Orbit Raising missions

Electric Orbit Raising (EOR) for telecommunication satellites has allowed significant reduction in on-board fuel mass, at the price of extended transfer durations. These relatively long transfers, which usually span a few months, cross large spans of the radiation belts, resulting in significant exposure of the spacecraft to space radiations. Since they are not very populated, the radiation environment of intermediate regions of the radiation belts is less constrained than on popular orbits such as LEO or GEO on standard environment models. In particular, there is a need for more specific models for the MeV energy range proton fluxes, responsible for solar arrays degradations, and hence critical for EOR missions. As part of the ESA ARTES program, ONERA has developed a specification model of proton fluxes dedicated for EOR missions. This model is able to estimate the average proton fluxes between 60 keV and 20MeV on arbitrary trajectories on the typical durations of EOR transfers. A global statistical model of the radiation belts was extracted from the Van Allen Probes (RBSP) RBSPICE data. For regions with no or low sampling, simulation results from the Salammbô radiation belt model were used. A special care was taken to model the temporal dynamics of the belts on the considered mission durations. A Gaussian Process (GP) model was developed, allowing to compute analytically the distribution of the average fluxes on arbitrary mission durations. Satellites trajectories can be flown in the resulting global distribution, yielding the proton flux spectrum distribution as seen by the spacecraft. We show results of the model on a typical EOR trajectory. The obtained fluxes are compared to the standard AP8 model, the AP9 model, and validated using the THEMIS satellites data.We illustrate the expected e ect on solar cell degradation, where our model is showing an increase of up to 20% degradation prediction compared to AP8.

Inner Radiation Belt Simulations of the Proton Flux Response in the South Atlantic Anomaly during the Geomagnetic Storm of 15 May 2005

A test particle simulation code was developed to simulate the inner proton belt response during the intense geomagnetic storm of May 15, 2005. The guiding center model was implemented in order to compute the proton trajectories with energy range 70-180 MeV. The time-varying magnetic field model implemented in the simulations was computed by the Tsyganenko model TS05 with the associated inductive electric field. One of the most important features of the Low-Earth Orbit (LEO) environment is the presence of the South Atlantic Anomaly, which imposes a dangerous radiation load on most of the LEO missions. The objective of this research is to investigate the proton flux variations in the anomaly region with respect to space weather conditions. The results showed that during the main phase of the geomagnetic storm, the proton flux in the SAA was decreased, whereas throughout the initial and recovery phases, the proton flux was increased at most of the altitudes. Numerical results were confirmed by satellite measurements.