Pioneering Evaluation of GaN Transistors in Geostationary Satellites

In this paper, we present the results of a 6-year experiment in space that studied the effects of radiation in GaN electronics in geostationary orbit. Four GaN transistors in a Colpitts oscillator configuration were flown in the Component Technology Test-Bed aboard the Alphasat telecommunication satellite. A heuristic analysis was performed by observing the variation in the power output of the oscillators with the total ionizing dose gathered during the mission. The total ionizing dose was measured with a RADFET placed close to the GaN devices. The experiment showed that GaN is a robust technology that can be used in the space radiation environment of a geostationary orbit. The work presented here starts with a brief introduction of the subject, the motivation and the main goal. This is followed by the description of the experimental setup, including the details of the oscillator design and simulations, as well as the implementation of the test bead and the Components Technology Test Bed. Finally, the results obtained during the 6 years of experience in space are discussed.

The Lunar Radiation Environment: Comparisons between PHITS, HETC-HEDS, and the CRaTER Instrument

Understanding the radiation environment near the lunar surface is a key step towards planning for future missions to the Moon. However, the complex variety of energies and particle types constituting the space radiation environment makes the process of replicating such environment very difficult in Earth-based laboratories. Radiation transport codes provide a practical alternative covering a wider range of particle energy, angle, and type than can be experimentally attainable. Comparing actual measurements with simulation results help in validating particle flux input models, and input collision models and databases involving nuclear and electromagnetic interactions. Thus, in this work, we compare the LET spectra simulated using the Monte Carlo transport code PHITS with measurements made by the CRaTER instrument that is currently orbiting the Moon studying its radiation environment. In addition, we utilize a feature in PHITS that allows the user to run the simulations without Vavilov energy straggling to test whether it is the root cause of erroneous phenomena exhibited in similar studies in literature. The results herein show good agreement between the LET spectra of PHITS and the CRaTER instrument. They also confirm that using a Vavilov distribution correction would ultimately provide a better agreement between CRaTER measurements and the previous LET spectra from the transport codes HETC-HEDS and HZETRN.

Multi-class Classification Method of Support Vector Machine Based on Error Correction Coding

In the space radiation environment, there will be many errors in the multi-classification results of support vector machine which caused by single event flipping , the ability of correcting classification errors through error correction coding is studied in this paper, results of simulation confirm that error correction coding can increase the accuracy ,which is beneficial for anti-single event flip.