Radiation Effects Analyses

Radiation effects analyses can include shielding analysis, total ionizing dose analysis, low dose rate analysis, proton fluence analysis, transient neutron analysis, photo-current burn out analysis, Single Event Upset analysis and EMP analysis.

A shielding analysis starts with the total ionizing dose impinging on the power supply. Then, the shielding effects of the mechanical structure are determined to arrive at the total ionizing dose experienced at each piece part. If additional shielding is necessary, this analysis determines the amount and location.

A total ionizing dose analysis considers the known effects of radiation on piece parts, such as the Vgs shift in power MOSFETs and the leakage current increases in semiconductors due to radiation induced defects. Pertinent post radiation parameters for each part are determined by researching parts data bases or from radiation lot acceptance test results. These effects of part degradation are analyzed using the SPICE Model and the worse case analysis.

Certain parts can be susceptible to very low dose rate effects. A low dose rate analysis examines potentially susceptible parts for adequacy and margin.

Ionizing radiation from proton or neutron fluence can cause some types of parts to be damaged more than they would be from an equivalent ionizing dose of gamma radiation. This effect can be analyzed and quantified.

Some space power supplies may be exposed to bursts of high energy radiation such as those produced by nuclear weapons. These bursts can cause circuit upset or burnout due to photo-currents. A transient radiation effects analysis considers these circuit upsets and a photo-current burnout analysis examines the circuitry for burn out potential. Nuclear events can also cause electromagnetic pulses (EMP). The adequacy of the power supply to resist burn out or malfunction caused by EMP may also be analyzed.