R.H. Maurer

RadFET Dosimeters in the Belt: the Van Allen Probes on Day 365

Van Allen Probes spacecraft VAP-A and -B, launched over a year ago [August 2012], carried 16 pMOS RADFETs into an orbit designed by NASA to probe the heart of the trapped-radiation belts. Nearly 350 days of in situ measurements from the Engineering Radiation Monitor (ERM) (a) demonstrated strong variations of dose rates with time, (b) found a critical correlation between its RADFET dosimeter and Faraday cup data on charged particles, and (c) mapped the belts by measuring variation with orbit altitude. This paper provides update on early results given in [1] along with details and discussion of the RADFET dosimetry analysed.

Radiation characterization of the ADSP2100A digital signal processor

A comprehensive radiation effects characterization of the Analog Devices ADSP2100A digital signal processor for the space environment has been completed using Californium fission fragments, laser light, heavy ions and protons. Results of these investigations led to the design of a latchup immune device that has been characterized with respect to SEU and total dose effects, as well as a thoroughly tested latchup protection and fault tolerant circuit. >

Neutron-induced pion production in silicon-based circuits

We compare deposition spectra from monoenergetic neutron irradiation to CUPID simulations of the same neutron exposures. CUPID does not agree with the experimental data unless pion production is included in the neutron-nucleon interaction. Pion-production events result in slightly more single-event effects (SEEs) for devices with relatively large sensitive volumes and low thresholds for upset but dramatically fewer events for the same sensitive volume when the threshold is high.

Applying new solar particle event models to interplanetary satellite programs

Variability in the models and methods used for single event upset (SEU) calculations in microelectronic memory devices can lead to a range of possible upset rates. In order to compare the Adams 1986 interplanetary solar flare model to a new model proposed by scientists at the Jet Propulsion Laboratory (JPL92) the authors have calculated an array of upset rates using heavy ion and proton data for selected DRAM and SRAM memories and for Actel Field Programmable Gate Arrays (FPGAs). To make more general comparisons of the models the authors have produced a set of engineering curves of predicted upset rates versus hypothetical device cross-section parameters. The results show that use of this more realistic, although still conservative, JPL model can have significant benefits for satellite programs, especially those which must operate continuously during solar particle events. The benefits include more flexibility in model choice, a higher level of confidence in the environment, and potential cost savings by the calculation of less pessimistic SEU rates which allow designers to integrate commercial products into their spacecraft design with the use of Error Detection and Correction (EDAC) schemes. >

Gallium arsenide solar cell radiation damage study

A thorough analysis has been made of electron- and proton- damaged GaAs solar cells suitable for use in space. It is found that, although some electrical parametric data and spectral response data are quite similar, the type of damage due to the two types of radiation is different. An I-V analysis model shows that electrons damage the bulk of the cell and its currents relatively more, while protons damage the junction of the cell and its voltages more. It is suggested that multiple defects due to protons in a strong field region such as a p/n junction cause the greater degradation in cell voltage, whereas the individual point defects in the quasi-neutral minority-carrier-diffusion regions due to electrons cause the greater degradation in cell current and spectral response. >

The susceptibility of electrodeless quartz crystal BVA resonators to proton ionization effects

The radiation susceptibility of an electrodeless (BVA) quartz crystal resonator of the AT crystalline cut is reported. It is shown that its sensitivity to low and high levels of proton radiation is less than that of an AT resonator with adhered electrodes. The effectiveness of preconditioning techniques is discussed, and an interpretation of the test results in terms of the materials aspects of the quartz electrode interface is given. >

A summary of recent VLSI SEU and latch-up testing (for space application)

As the complexity of satellite systems increases, interest in using highly integrated microelectronic devices also increases. The SEU and latch-up characteristics of these devices are usually not known. Therefore, thorough testing should be performed on an VLSI device that is considered for use in space systems. The authors detail the results of a series of SEU and latch-up tests on VLSI devices of interest for use in future satellite systems and describe their test system designed to efficiently perform these tests.<<ETX>>

Portable real time neutron spectrometry

We describe the early stage of development of an engineering model portable, real-time neutron spectrometer. Several systems of two distinct detector types, a helium 3 gas filled proportional counter and a bulk silicon solid state detector, will be necessary to cover the energy range from thermal to 500 MeV. The advantages and disadvantages of using a moderator were investigated experimentally.