Comprehensive Charging and Material Characterization Services for Space Missions

The space environment is dynamic, complex, and harsh, leading to possible mission failures. Energetic charged particles emitted by the sun pose the biggest risk to a spacecraft and its components. A buildup of these particles can potentially alter a spacecraft’s material properties leading to electrostatic discharge (ESD) related arcing, degraded insulators, and other undesirable effects. Figure 1 show arc damage on a satellite caused by unmitigated ESD.

Fig. 1. Arc damage from the ADEOS-II Satellite caused by unmitigated ESD. Courtesy: NASA.

Another challenge is that different orbits have different energy densities and particle distributions causing different effects. Because of this, it is important to know how materials will behave as they age based on where they will be living in space. The space industry has vast knowledge regarding specific details of what comprises various space environments (LEO, GEO, Lunar, etc.). For example, data shows low conductivity or insulating materials as significant risk areas in most orbits.

Fundamental material properties govern whether or not charge will build at the surface (surface charging) or deep within bulk materials (internal charging). The energy of incident particles also plays a role in how far they can penetrate non-conductive or low conductivity materials. Material thickness, especially for covers, will determine how many particles (dose) an object may encounter throughout its lifetime.

Fig. 2. Space radiation environment.

EMA has a large suite of charging and material characterization efforts. The time frame for such testing is dependent on materials and size of the spacecraft. The following details how EMA performs material properties and charging testing.

Space Environment and Radiation Effects Test Chamber

EMA completes charging and material characterization efforts using our Space Environment and Radiation Effects (SERE) commercial test chamber. SERE specializes in in-situ charging studies of spacecraft components and instrumentation to help determine the risk level for various space environments.

Our radiation sources are capable of exposing materials to the equivalent total ionizing doses they will see throughout their mission lifetimes. This allows materials to be aged and evaluated equivalent to what would happen at various orbits.

Current radiation sources include:

• An electron flood source that produces energies between 500eV- 100keV with fluxes measurable down to 5pA/cm² and a max output of 5nA/cm² with beam uniformity staying within 80% of max with a 13”x13” square.

• A low plasma generator with an incorporated magnetic filter that produces 5-20eV along with sub-eV electron to mimic the low earth orbit plasma environment. This generator can be used with various gases and output currents to produce densities that range from 1×10¹³ – 1×10⁸ #/m³.

• A VUV Krypton arc lamp with a continuous spectrum from 125-165nm and an additional peak at 116nm that can be used for surface neutralization and lower end solar simulation.

To learn more about SERE click here, the chamber is shown in Figure 3 below.

Fig. 3. EMA’s Space Environment and Radiation Effects commercial test chamber, also known as SERE.

Experiment Design

To start, EMA will design the experiment by determining the onset of RIC and charging rates. This decides the specific energies acceptable to accelerate the aging process of materials allowing for more precise testing and results.

As a part of designing the experiment, we will identify the various samples needed for each material property measurement to allow for mounting and sample holding, transfer mechanisms (between chambers for various parts of the project), and data logging set up. Properties such as size and temperature dependence will be factored into the experiment.

Test Procedure

Before any testing starts, it is necessary to define the procedure for each analysis. EMA will divide the formal test procedure by the specific test or measurement performed. This approach ensures traceability for each experiment and clarifies how to run it. EMA will review both the experiment design and test procedure with you prior to beginning any testing. We will include sample quantities, various environments, charging rates and energies, measurements, test setups, and data in the test procedure report.

Material property Measurements

EMA can provide the following material property measurements:

• Reflectivity/ emissivity
• CVC conductivity (bulk)
• Ambient/ surface conductivity
• Permittivity
• ESD onset
• Radiation induced conductivity
• Electron yield
• Photo yield
• Ion yield

Measurements include pristine and end of life results, including from Lunar Orbit and Radiated Belt Transient exposures. We will design experiments and define realistic and necessary temperature selections for each of the material measurements performed. Each measurement includes the necessary efforts to irradiate/ age the various samples. EMA will keep laboratory logs throughout testing to provide a time history (if needed) of the testing, and the data package/ report will include photos and necessary set-up details.

Surface and Internal Charging

EMA will provide testing to evaluate the risk and characterization of ESD-related arcing on connectors and cable harnesses in required environments as described in SLS-SPEC-159 Rev. H. You can also use the data obtained during this test in other tasks throughout the program.

Just as material properties change with radiation exposure, so do the surface and internal charging effects. EMA will use samples of different mission duration ages for this testing. We will evaluate the surface and internal charging effects for pristine and full mission aged samples.

Model Validation

EMA will include Ansys Charge Plus models of the product under consideration. The material property measurements, along with ESD data, will be fed into the models and validated.

Charge Plus combines electromagnetic solvers, fluid solvers, and particle physics solvers for easy-to-use multiphysics simulation. It properly considers gas-phase interactions, chemical reactions, and particle-physics effects that are critical for plasma dynamics. Application areas include space plasma environments and radiation effects, ESD, arcing (plasma in air), and semiconductor processing plasmas. Learn more by clicking here.

Summary Report

At the conclusion of the test campaign, EMA will prepare a formal test report to summarize all the experiments, test setups, and results obtained through the test campaign.

Get STarted

Each test campaign is different and tailored for each customer and product. Reach out now to see how EMA can support you to get your projects off the ground faster without going over budget. Contact us by clicking here.