Space missions expose spacecraft electronics to complex space environments, including charged particle fluxes, solar wind plasma, and high-energy radiation, which can induce surface charging, electrostatic discharges (ESD), and single-event upsets (SEUs) in power conversion systems. Traditional mitigation strategies, such as radiation-hardened components and shielding, offer partial protection but incur significant mass and efficiency penalties and do not address transient plasma-induced disturbances. This study presents a physics-informed, plasma-resilient design methodology for DC-DC converters in deep-space applications. A comprehensive space-environment simulation framework is developed to model heliocentric plasma density, solar wind velocity, proton energy spectra, and surface charging, incorporating both low- and high-frequency fluctuations. Building on this, a radiation-aware, adaptive DC-DC converter topology is proposed, coupled with a model reference adaptive control (MRAC) architecture and disturbance observer, enabling real-time mitigation of plasma-induced voltage fluctuations, SEU step events, and input ripple. Simulation results demonstrate that the proposed approach maintains the output voltage close to the nominal value under the considered space-environment disturbances. The adaptive controller reduces the RMS voltage error from approximately 10.3-12.6 V in the uncontrolled system to approximately 1.86-1.91 V across the investigated operating scenarios while significantly suppressing transient deviations caused by plasma fluctuations and SEU events. Frequency-domain analysis confirms effective attenuation of low-frequency plasma-induced transients, while Lyapunov-based stability proofs ensure guaranteed closed-loop robustness. The integrated methodology enables reliable, efficient, and adaptive energy management for long-duration space missions, highlighting the importance of environment-aware hardware-control co-design for future deep-space spacecraft.
Backside-illuminated CMOS image sensors (BSI CIS) exhibit complex total ionizing dose (TID) effects due to the existence of several dielectrics surrounding the pinned photodiode. It is of importance to clarify the contributions of distinct oxides to the TID response. gamma-rays irradiation experiments and TCAD simulations on BSI CIS were performed. Simulation results were calibrated with experimental results. It is shown that the dominant contributors to dark current are the transfer gate oxide and backside oxide on the BSI CIS at several hundred krad(Si) and several Mrad(Si), respectively. A dynamic full-well capacity phenomenon is observed at low TID levels, and this phenomenon is a result of dynamic equilibrium between the pinned photodiode and floating diffusion. It is demonstrated that the physical mechanism of quantum efficiency (QE) degradation is due to surface recombination at the backside oxide regardless of short and long wavelengths. The simulation results of QE degradation are in agreement with the experimental results.
This study investigates radon (Rn-222) concentrations within 21 residential buildings and the associated radiological health risks of radiation in Al-Gharraf district, Dhi Qar Governorate. Using CR-39 nuclear track detectors, radon levels were measured in various dwellings, with concentrations ranging from 73 +/- 29 to 336 +/- 82 Bq m(-3), and a mean value of 151 +/- 52 Bq m(-3). Radiological assessment revealed a mean annual effective dose (AED) of 3.8 mSv y(-1) and a mean pulmonary dose (D-lung) of 6.0 mSv y(-1). Statistical analysis using Pearson correlation coefficients revealed a strong and statistically significant positive correlation between radon concentration and relative humidity (r = 0.815, p < 0.01), while maximum and minimum temperatures showed moderate positive correlations (r = 0.561 and r = 0.490, respectively). In contrast, outdoor wind speed exhibited a weak and statistically insignificant negative correlation (r = -0.209) with indoor radon levels, which serves as a general observational indicator rather than a direct causal relationship due to unmeasured indoor ventilation dynamics. The findings indicate that while average radon levels remain within international ranges, peak concentrations in certain dwellings exceed the WHO recommended reference level. These results emphasize the significant influence of environmental factors, notably relative humidity, on indoor radon dynamics. Consequently, improving ventilation strategies is essential to mitigate long-term inhalation risks. This study establishes a vital radiological baseline for the Al-Gharraf region and contributes to the Iraqi national radon database, supporting future environmental health policies and risk assessment frameworks.
