Search

Single event upset effect is an important factor that causes performance degradation and functional failure of aerospace equipment components in space radiation environment. When high-energy particles incident on semiconductor devices in working state, they will induce functional errors of devices and even cause permanent damage. Based on the finite element method, the three-dimensional simulation of Metal-oxide-semiconductor field-effect transistor (MOSFET) is carried out. The single event upset effect of MOSFET under heavy ion irradiation and the influence of heavy ion irradiation on transient drain current are investigated. The results show that the transient drain current of MOSFET devices will increase rapidly when heavy ions are incident, and then the logic state of the devices will change. With the increase in linear energy transfer density, the peak value of the transient drain current pulse increases and the pulse width decreases. With the increase in the incident angle, the peak value of the pulse first increases and then decreases. The maximum value is obtained when the incident angle is vertical, the pulse width first decreases and then increases, and the minimum value is obtained when the incident angle is vertical. With the increase in MOSFET size, the difference of transient drain current formed by symmetrical heavy ion incidence is becoming smaller and smaller. When the incident track is completely in the drain region, the simulation results are the same. [ABSTRACT FROM AUTHOR]

Secondary electrons (SEs) of high-energy cosmic rays in high-altitude areas can cause irradiation damage to insulators. In this paper, the Monte Carlo method is utilized to analyze the energy loss of SEs irradiated by extensive air showers in insulators. We investigate the formation of electron–hole pairs in insulators, the influence on the insulation characteristics, and the physical mechanism of the process. The results show that the energy of the SEs is much greater than the energy of the electrons in the transmission line, which may pose a threat to the equipment of a power system, and the energy loss of the incident electrons in insulators with different energies shows different characteristics. When the electron energy is lower than 364 keV, displacement damage will not occur in the insulators, and the insulation characteristics will not change; when the electron energy is between 364 keV and 723 keV, electron–hole pairs are generated in insulators but without damage cascade, which will have little impact on the insulation characteristics; when the electron energy exceeds 723 keV, damage cascade will occur, along with many electron–hole pairs, and the insulator insulation characteristics will be greatly affected. [ABSTRACT FROM AUTHOR]

Vibrational–translational (V–T) relaxation is quite common in molecular nitrogen discharge non-equilibrium plasmas. In this paper, the energy relaxation in V–T transition is investigated by master equation modeling on all vibrational levels below the dissociation limit. The state-to-state transition rates are calculated by a forced harmonic oscillator (HO)-free rotating model. Meanwhile, the classic Landau–Teller model based on the HO of vibrational levels is revisited. First, the V–T relaxation in a heat bath is compared between the HO model, Morse's anharmonic oscillator (AHO) model, and realistic vibrational levels by a direct-potential-fit analysis of spectroscopic data. The relaxation of average vibrational energy using the AHO model is faster than that using the HO model. Then, the influence of more frequent vibrational–vibrational (V–V) collision on the V–T transition in the heat bath is investigated by using different numbers of vibrational levels. The anharmonic effect is significant with more vibrational levels. Finally, the V–T energy transfer is modeled by a coupled solution to master equations and gas heating. The stronger the non-equilibrium between vibrational and translational temperature in the beginning, the larger the difference that can be obtained between the HO model (Landau–Teller theory) and realistic vibrational levels. [ABSTRACT FROM AUTHOR]

Electron transport coefficients in copper vapor plasma are calculated both by two-term expansion of electron Boltzmann equation Bolsig+ and tracking the random motion of electrons using Monte Carlo collision code METHES based upon recently evaluated cross section sets. The copper atoms are evaporated from hot electrode during the post-arc phase of vacuum circuit breakers, in which Townsend breakdown between electrode gaps is probable. The electron energy probability function, electron mean energy, flux/transport mobility and diffusion coefficients, as well as Townsend ionization coefficients are shown in reduced fields 10∼1000 Td at a typical vapor temperature 2000 K. The validity of two-term approximation is checked by comparison to well benchmarked METHES code. If the electrode temperature varies between 1500∼2500 K, the influence of vapor temperature on ionization coefficients is about 5% at 200.4 Td, and drops to 0.5% at 493 Td according to Bolsig+ results. Similar to classic gas discharge theory, the Paschen curve is proposed for Townsend breakdown of metal vapor. Using the calculated ionization coefficient and a constant secondary electron yield, the Paschen minimum is determined to be 106∼122 V at a critical value of the product of vapor density and gap length (4.7∼5.7)×1019 m-2. A satisfactory agreement was found with the previously measured ignition voltage between vacuum interrupter contacts after the arcing. [ABSTRACT FROM AUTHOR]