The Magnetic Loop Antenna (MLA) C. Cavoit – A. Marchaudon / CNRS-LPC2E Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Summary MLA Accommodation Sensitivity to the E field Conclusion Principle, preamplifier Electronic components: radiations, temperature Accommodation Influence of the proximity of a SC on the MLA’s TF Noise induced by a FG at the MLA’s location Sensitivity to the E field Presence of a conductive pipe Conclusion Status of the development of the MLA Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Functioning Principle Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Preamplifier Tolerance to the radiations (TID): IF1320 (Interfet) tested by LPC2E in 2008 up to 250kRad RHF310 (ST Microelectronics) RadHard up to 300kRad (+SE) Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Ability to work at (very) low temperature Magnetic core Known only from -50°C Need to be tested at lower temperature MLA need to be calibrated at several temperatures Active components Known only from -55°C Whole preamplifier need to be tested at lower temperature Determination of the working threshold Assemblies (mechanical & electrical) Pertinent choice Test Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Specifications Size: 205 x 215 x 55mm Mass: 250g Power: Voltage: +/- 5V regulated Current: +/- 20 mA Heater: TBD The specifications are subject to change until the end of all preliminary tests Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Accommodation What is the minimum distance required between 2 magnetic sensors to ensure a proper operation for both ? => 2 sets of tests Recording of the MLA’s TF without and with a presence (ON or OFF) of a SC (and vice-versa) Recording of the MLA’s noise without and with the presence of a working FG Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Used Sensors MLA CHARM model SC (permalloy) DEMETER model (3 axis) SCDB (ferrite) Bepi-Colombo (1 axis) FG (ring core) Former model (Mars-96 / 3 axis) Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

First set: setup Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

First set, Result 1: MLA-SC Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

First set, Result 2: MLA-SCDB Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

First set, Result 3: SC-MLA Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

First set, Result 4: SCDB-MLA Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Second set: setup Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Second set, Result 1: MLA-FG Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Second set, Result 2: MLA-FG Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Second set, Result 3: SC-FG Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Sensitivity to the E field: setup Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Sensitivity to the E field: Result Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Conclusion 1: what is done Design The electronic active components withstand at least 250kRad The temperature sensor inside the electronic box is mandatory and a heater is likely inescapable. Accommodation No influence of a SC on the MLA’s operation at any distance (and vice versa), thus they can be placed very close to each other. The noise induced by a FG remains very large, so it should be located at at least 1m away from MLA to take benefit of its good sensitivity. Nevertheless the noise added by the cable going along the boom should not be a concern. MLA should also placed far away from the spacecraft for the same reasons although we don’t now its noise level (Noise < 1E-15T @ 1MHz at the MLA’s location) Sensitivity to the E field Using a metallic boom will increase dramatically the MLA’s sensitivity to the E field. Using a non conductive boom coated by a poor conductive material could be appreciated. Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA

Conclusion 2: what is remaining to do Design Find out the temperature working threshold of the preamplifier Test the magnetic core down to this temperature Test the electrical assembly of the loop down to this temperature Thermal study Make a thermal model of the electronic box Definition of the heater Mechanics Test the mechanical assemblies, cables, connectors down to -230°C Warsaw, 10-11 jan 2011 RPWI Team Meeting / MLA