E.2.5 The solar panel simulation device

E.2.5.1. The test set-up

The complete test set-up is as follows.

With such a device, it was feasible to conduct electrostatic discharge tests in normal situation (the sample structure is connected to the ground and the dielectrics are charged) or in inverted voltage gradient mode.

Under certain environmental conditions, the satellite is charged negatively to several kilovolts and the resulting discharges are discharges of metallic origin when the structure discharges. In a laboratory, the representativity of such discharges is obtained by biasing the structure of the samples between –3 500 V and –5 000 V. It is important that the complete measurement and current injection device are also referenced to this voltage. During the measurements, all the devices are thus strongly negatively biased.

E.2.5.2. The flash-over current simulation

The flashover current starts during the blow-off. This current is collected on the cathode at the discharge site.

To simulate this phenomenon correctly, a special power supply (coverglass simulator in Figure E-10) delivering a triangular current shape is added and connected to this electrode. The current delivered by this source is intended to be sufficient to maintain the conductive plasma between the electrodes at the discharge site during the flashover.

Figure E-10: Setup simulating the satellite including flashover current

E.2.5.3. What is simulated and what is not, discrepancy with the real case

This test allows one to evaluate if the Solar Array is able to support without damage the self powered secondary arc in real space conditions. It reproduces as exactly as possible the real current shape which occurs during this phenomenon.

The current is fully representative of both what happens at the discharge site and the inrush current through the components when the discharge occurs.

However the direction of the static current through the diodes can be reversed compared with the real case depending where it happens. So if component destruction occurs during this test this may not have happened in a realistic way. In any case this simulation cannot be considered as an electrical susceptibility test which is done during a dedicated EMC test in air.