Modeling solar cell degradation in space: A comparison of the NRL displacement damage dose and the JPL equivalent fluence approaches†

Abstract

The method for predicting solar cell degradation in space radiation environments developed recently at the US Naval Research Laboratory (NRL) is compared in detail with the earlier method developed at the US Jet Propulsion Laboratory (JPL). Although both methods are similar, the key difference is that in the NRL approach, the energy dependence of the damage coef®cients is determined from a calculation of the nonionizing energy loss (NIEL) and requires relatively few experimental measurements, whereas in the JPL method the damage coef®cients have to be determined using an extensive set of experimental measurements. The end result of the NRL approach is a determination of a single characteristic degradation curve for a cell technology, which is measured against displacement damage dose rather than¯uence. The end-of-life (EOL) cell performance for a particular mission can be read from the characteristic curve once the displacement damage dose for the mission has been determined. In the JPL method, the end result is a determination of the equivalent 1 MeV electron¯uence, which would cause the same level of degradation as the actual space environment. The two approaches give similar results for GaAs/ Ge solar cells, for which a large database exists. Because the NRL method requires far less experimental data than the JPL method, it is more readily applied to emerging cell technologies for which extensive radiation measurements are not available. The NRL approach is being incorporated into a code named SAVANT by researchers at NASA Glenn Research Center. The predictions of SAVANT are shown to agree closely with actual space data for GaAs/Ge and CuInSe 2 cells¯own on the Equator-S mission.

Electronic and Optical Properties of Energetic Particle-Irradiated In-rich InGaN

“…We used the displacement damage dose methodology developed by the Naval Research Laboratory for modeling solar cell degradation in space environments to scale the irradiation damage [14,15]. The displacement damage dose (D d , in units of MeV/g) is defined as the product of the non-ionizing energy loss (NIEL) and the particle fluence.…”

Radiation tolerance of opto-electronic components proposed for space-based quantum key distribution

“…where φ p is the fluence of protons with energy E, and S p is the corresponding NIEL [7]. A detailed discussion on the estimation of the DDD and its conversion to equivalent days in orbit is available at [8].…”

High efficiency, radiation-hard solar cells

“…Particle doses were converted to non-ionizing energy loss (NIEL) using the methodology developed by the Naval Research Laboratory by using either standard tables for proton [Messenger et al, 2000] and electron irradiation or the SRIM program for the case of alpha particles [Messenger et al, 2002]. The NIEL was then used to calculate the corresponding displacement damage dose (D d , units of MeV/g).…”