Table of Contents ECSS Model Page
Background Information Radiation sources and effects
MC-SCREAM

Solar cells are subject to degradation by exposure to proton and electron radiation. In addition to EQFLUX, SPENVIS provides access to a method for implementing the displacement damage dose (DDD) methodology for calculating end-of-life (EOL) solar cell performance in space. A major component of the DDD methodology is the use of non-ionizing energy loss (NIEL) in radiation damage correlations, of which the calculation has been verified by several different groups worldwide. There are four basic components involved in implementing the DDD method for solar cell EOL studies:
  1. determination of the incident radiation spectra,
  2. calculation of the corresponding attenuated radiation spectra after having passed through shielding of known thickness
  3. calculation of the total DDD for the mission of interest and
  4. determination of the expected solar cell degradation.

There is a need in the space solar cell community for an alternate approach to model and predict EOL performance of solar arrays in a space radiation environment. The DDD methodology can provide such an alternate without losing any accuracy and fidelity. Previous work has validated the DDD methodology against both measured space data [Morton et al., 1999, Messenger et al., 2000] and calculations performed using the equivalent fluence methodology developed by NASA JPL [Messenger et al., 2001]. For several years, the space solar community has considered general implementation of the DDD method, but no computer program exists to enable spacecraft engineers to readily implement the model. In a collaborative effort, the US Naval Research Laboratory (NRL), NASA and OAI have previously produced the Solar Array Verification and Analysis Tool (SAVANT) under NASA funding, but this program has not progressed beyond the beta-stage and is now considered to be inaccurate [Walters et al., 2005].

The MC-SCREAM application in SPENVIS [Messenger et al., 2008] implements the DDD methodology in a format complementary to that of SAVANT, using MULASSIS simulations and fluences predicted by the trapped radiation models for Earth or Jupiter and the solar proton flux models.

User can choose between pre-defined cell types and a manual input of solar cell parameters. In addition the cover glass thickness has to be specified. For manual input, the cell layer materials and thicknesses have to be specified.
Advanced users have the option to specify more than one cell layer.

For manual input of the solar cell definition, NIEL parameters for protons and electrons have to be specified. The check boxes in the NIEL parameters table control whether the degradation parameters for the respective configurations will be calculated or not.

Radiation environment specification

The parameter page for MC-SCREAM checks whether the trapped particle or solar proton models have been run.
Advanced users have the option to make a selection of the input particles, and to modify some of the parameters for the MULASSIS run.

When the input form has been completed, pressing the button will start the calculation and bring up the "Results" page.

Warning: using these buttons deletes all existing output from the MC-SCREAM tool, in order to ensure consistency in the outputs.

Results

MC-SCREAM produces the files listed in the table below. A description of the format of the files can be brought up by clicking on their description in the table.

Output files generated by MC-SCREAM
File name Description
spenvis_scr.txt Report file
spenvis_scp.txt Log file
spenvis_sco.txt Detailed output file
spenvis_scr.wrl VRML representation of the geometry

References

Messenger S.R., Walters R.J., Summers G.P., Morton T.L., LaRoche G., Signorini C., Anzawa O. and Matsuda S., Displacement Damage Dose Analysis of the COMETS and Equator-S Space Solar Cell Flight Experiments, Proc. 16th European Photovoltaic Solar Energy Conference, 1-5 May 2000, Glasgow, UK, 2000.

Messenger S.R., Summers G.P., Burke E.A., Walters R.J. and Xapsos M.A., Modeling Solar Cell Degradation in Space: A Comparison of the NRL Displacement Damage Dose and the JPL Equivalent Fluence Approaches, Progress in Photovoltaics: Research and Applications 9, 103-121, 2001.

Messenger, S.R., Walters, R.J., Warner, J.H., Evans, H., Taylor, S.J., Baur, C. and Heynderickx, D., Status of Implementation of Displacement Damage Dose Method for Space Solar Cell Degradation Analyses, , 2008.

Morton T.L., Chock R., Long K., Bailey S., Messenger S.R., Walters R.J. and Summers G.P., Use of Displacement Damage Dose in an Engineering Model of GaAs Solar Cell Radiation Damage, Tech. Digest 11th Intl. Photovoltaic Science and Engineering Conference, Hokkaido, Japan, pp. 815-816, 1999.

Walters R.J., Summers G.P., Messenger S.R. and Morton T.L., SAVANT Analysis of the Microelectronics and Photonics Testbed Solar Cell data. Progress in Photovoltaics: Research and Applications, 13, 103-113, 2005.

Last update: Thu, 16 Jun 2022