Electromagnetic Interference Caused by Plasma Plumes (EPCOMSIM) – ESA CSC: Connectivity & Secure Communications

Objectives

The EPCOMSIM study was carried out to quantitatively assess the impact of plasma plumes generated by common ion thrusters (SPT-100, PPS-1350, HEMP-T) on the RF comlink of a geostationary telecommunications satellite.

Ion thrusters offer a high specific impulse making them attractive for station keeping manoeuvres of geostationary satellites. The satellite corners are an attractive position to mount the thrusters where they fire within the field-of-view of the payload reflector antennas for an extended period of time. Instabilities within the plasma plume could modulate onto the RF carrier and in turn degrade signal quality. The impact must be known to guarantee the performance of the mission.

The objective of the EPCOMSIM study was two-fold:

To obtain measurement results of the spurious modulation induced by a plasma plume on a RF carrier by means of representative test setups,
To develop and validate (against measurements) a simulation tool for modelling of the plasma plume interference.

Point 1 required the development of a stable mechanical+electrical setup inside the chosen vacuum facility (IV10 of Alta in Pisa, Italy, the largest vacuum chamber available in Europe for electric propulsion testing), a RF acquisition system able to work within the highly reverberating environment inside the vacuum chamber and the RF test setups themselves.

Point 2 required the development of detailed plume models of the three test thrusters (SPT-100, HEMP-T and PPS-1350) and on the electromagnetic side the development of an EM solver tailored to the specific problem. The EM solver was integrated into the software Antenna Design Framework-ElectroMagnetic Satellite (ADF-EMS) by IDS to have an easy to use interface.

Challenges

The following key issues have been addressed in the EPCOMSIM study.

Simulation activity:

Plume modelling under unsteady boundary conditions,
Numerical efficient EM model for the plume-wave interaction,
Efficient modelling workflow for the user of the simulation tool.

Test activity:,

RF acquisition system inside vacuum chamber (time gating),
Test setup design for the basic test featuring rails to allow a ‘tomographic’ scan of the plasma plume,
Test setup design for the advanced test featuring four reflector antennas with mechanical adjustment capability, high-frequency Langmuir probes and three ion thrusters.