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Total Ionizing Dose Testing
Scope and Description
This topic covers total ionizing dose (TID) testing of spacecraft components and assemblies. In space, hardware is exposed to significantly elevated levels of ionizing radiation, mostly due to electrons and protons. This can result in performance degradation or failure of common spacecraft components, including semiconductors, solar cells, and optical fibers. TID testing is necessary if a component-type is susceptible to total dose effects and TID test data is not available. TID testing can be high dose rate or low dose rate/ELDRS. The goal of TID testing is to characterize parameter variations over total dose and to determine the threshold where component performance no longer meets mission requirements.
Resources under this topic area are primarily links to test facilities, testing/planning guidance, and standards that provide traditional TID test methods.
Best Practices and Lessons Learned
- A statistically significant quantity of devices should always be tested and, if possible, all devices should have the same date/lot code.
- Within a device test lot, it is often advantageous to test half of the devices in a biased (or powered) configuration and half in an unbiased (or unpowered) configuration.
- If possible, use data acquisition hardware to continually measure and plot relevant device parameters for real-time observation and post-test analysis. The ability to view results in real time allows for test conductors to deviate from the test plan if necessary.
- Include at least one unirradiated "control" device in the test lot. This control device is useful in proving out the test setup and validating observations.
- Affix unique labels to all devices, including the "control" so that they can be easily identified and observations/results can be quickly recorded in test logs.
- TID test facilities are heavily shielded. This often requires that test setups implement long cable runs between the device under test (DUT) and test support equipment. It is recommended that power supply sense lines are used to regulate voltage close to the DUT and data interfacing is achieved via Ethernet or USB extenders when practical.
- Even if devices are found to exhibit complete failure at a certain TID threshold, functionality may return after a period of annealing. If functionality does return, that is a useful finding that can help to inform on-orbit performance predictions. Always conduct post-irradiation functional testing of failing devices after a substantial period of time to determine if complete or partial functionality returns.
- After testing is complete, a report detailing the test setup, exposed devices, high-level results, and test data logs should be created. This report should also include pictures, oscilloscope screenshots, and facility generated logs/plots when available/permitted.
- If the DUT has built-in power saving functionality, ensure this functionality is disabled or the device may automatically toggle the bias of internal hardware during exposure and skew results.
Radiation Test Solutions
This website provides information from Radiation Test Solutions (RTS) regarding radiation effects testing. ... They provide a useful introductions to radiation effects, the hazards of the space environment for electronics, and the related testing standards and protocols currently utilized across the industry.
Standards for Radiation Effects Testing: Ensuring Scientific Rigor in the Face of Budget Realities and Modern Device Challenges
Slide 7 of this NASA presentation includes a comprehensive list of "Key Space Radiation Test Standards". ... Slide 8 includes a table of "Space Radiation Test Guidelines" which references useful guides and best practices related to the TID and SEE testing of EEE parts for spaceflight. This resource also aims to present examples of shortcomings in such test standards resultant from the constant evolution of technology.
This website provides useful links to NASA-furnished radiation effects resources and a list of radiation ... test facilities.
This website is the primary source of information regarding the NASA Goddard Space Flight Center (GSFC) ... Radiation Effects Facility (REF). REF is located in Greenbelt, MD and supports TID testing for government, industry, and university customers. Their site includes points of contact for cost and scheduling, information on the various radiation sources (i.e. medium dose rate and ELDRS), and high-level experiment setup requirements.
Virginia Power Technologies (VPT)
The VPT Radiation Laboratory and Test Services provide TID sources for evaluating aerospace electronics. ... Their facility is located in Chelmsford, MA and offers both low-dose rate (LDR) and high-dose rate (HDR) sources.
Thomas Turflinger et al.
This presentation provides background on the various TID testing methods widely implemented across the ... industry as well as an abridged summary of these test methods. This presentation goes on to make a case for updates to MIL-STD-883 Test Method 1019.9 in order to arrive at a technically correct and more cost-effective method. These details are summarized on Slide 24.
This test method defines basic requirements which are applicable to the total dose testing of semiconductor ... devices. It is split into two objectives: the TID evaluation of a technology and the qualification and lot acceptance testing of high reliability devices. For both of these objectives, this concise resource provides straightforward guidance regarding sample selection, test fixture design, device bias conditions, measurement time intervals, and in-situ testing. Additionally, this resource provides a step-by-step exposure and test sequence and notes on results reporting.
US Department of Defense
The section titled "Method 1019.9 Ionizing Radiation (Total Dose) Test Procedure" of this standard provides ... a widely accepted procedure for conducting total dose testing of microcircuits using a Cobalt-60 (Co-60) gamma ray source. The procedure presents four tests and their respective applicability. It also includes helpful sections on test setup and configuration. This includes cabling, dosimetry, sample selection and handling, lead and aluminum containers, etc.
Doug Sinclair et al.
This white paper provides a "Careful COTS" approach to component selection and testing as they both relate ... to radiation effects and smallsat missions. The presented approach is particularly applicable to LEO missions that leverage COTS components.