Engineering topics
Publications and source records attributed to Ladbury, R. L..
A confidence level based approach to total dose radiation hardness assurance is presented for spacecraft electronics. It is applicable to both ionizing and displacement damage dose. Results are compared to the traditional approach that uses radiation design margin and advantages of the new approach are discussed.
This study was being undertaken to determine the single event effect susceptibility of the commercial Vishay 60-V TrenchFET power MOSFET. Heavy-ion testing was conducted at the Texas AM University Cyclotron Single Event Effects Test Facility (TAMU) and the Lawrence Berkeley National Laboratory BASE Cyclotron Facility (LBNL). In addition, initial 200-MeV proton testing was conducted at Massachusetts General Hospital (MGH) Francis H. Burr Proton Beam Therapy Center. Testing was performed to evaluate this device for single-event effects from lower-LET, lighter ions relevant to higher risk tolerant space missions.
We develop metrics for assessing the effectiveness of proton SEE data for bounding heavy-ion SEE susceptibility. The metrics range from simple geometric criteria requiring no knowledge of the test articles to bounds of SEE rates.
Variability of the space radiation environment is investigated with regard to parts categorization for total dose hardness assurance methods. It is shown that it can have a significant impact. A modified approach is developed that uses current environment models more consistently and replaces the design margin concept with one of failure probability.
We investigate the use of commercial FPGA based evaluation boards for radiation testing DDR2 and DDR3 SDRAMs. We evaluate the resulting data quality and the tradeoffs involved in the use of these boards.
We develop single-event risk Prior probability distributions based on historical and heritage data. The Priors can be used to bound single-event effects risk for testing, part selection and design.
We investigate whether bias conditions arid electrical and thermal stresses can affect the Total Ionizing Dose response ofDDR2 SDRAMs
The relative importance of heavy-ion interaction with the oxide, charge ionized in the epilayer, and charge ionized in the drain substrate, on the bias for SEGR failure is experimentally investigated.
A Technology Computer Aided Design (TCAD) simulation-based method is developed to evaluate whether derating of high-energy heavy-ion accelerator test data bounds the risk for single-event gate rupture (SEGR) from much higher energy on-orbit ions for a mission linear energy transfer (LET) requirement. It is shown that a typical derating factor of 0.75 applied to a single-event effect (SEE) response curve defined by high-energy accelerator SEGR test data provides reasonable on-orbit hardness assurance, although in a high-voltage power MOSFET, it did not bound the risk of failure.
No abstract available