Solar Probe Plus – FIELDS Main Electronics Package Instrument Pre-Environmental Review EMC Keith Goetz University of Minnesota Goetz@umn.edu 10 April 2017

SPP/FIELDS MEP Two Sides Each has a Spacecraft I/F Each has a Magnetometer Each has Antenna Biasing Each has a Power Supply FIELDS1 also has Data Controller Board Radio Frequency Spectrometer Digital Fields Board SCM Calibration Control Absolute Time Sequencer TDS I/F FIELDS2 also has Time Domain Sampler DCB I/F SWEAP I/F MEP

SPP/FIELDS Unchanged from CDR Five voltage sensors V2 electric antenna Unchanged from CDR Five voltage sensors Two Fluxgate magnetometers One Search-Coil Magnetometer Main Electronics Package V3 electric antenna MAGi, MAGo MEP V4 electric antenna V5, SCM V1 electric antenna

MEP – Buttoned Up

Environmental Testing EMC Here’s trouble – 10 February 2017 As part of conducted susceptibility testing (CS01) Test calls for a 1 Vpp sine wave atop the S/C power bus (32VDC) We inadvertently applied a much larger sine wave – tests suggest 70 Vpp LNPS1 operational power supply failed instantly – no current Slice was returned to UMN First stage 12V buck-coil converter was replaced – unit returned to full functionality ~20 EEE parts identified as possibly affected by the voltage extreme – replaced Conformalled and inspected (via photography) Temperature testing (in air) Fully functional – all supply voltages matched previous calibrations Failed part is out for DPA Slice was returned to UCB and MEP BB converter tested with a variety of torture Part worked normally up to 70V but failed abruptly at 80V Monitors on the 12V inner stage showed no trace of voltages above 12V Further CS testing to be done on high fidelity EM

Magnetic Sniff Materials all clean Flight hardware verified as clean A286 on boom verified as non-magnetic Flight hardware verified as clean

Isolation All greater than 1 MΩ FIELDS1 power interfaces Operational Heater FIELDS2 power interfaces All greater than 1 MΩ

Bonding MEP to copper plate – 1.6 mΩ V1234 EM enclosures ~4mΩ Not flight-like

Transients In-rush current measured high Waiver in place

CE01/CE03 Performed on EM MEP, EM V1234, EM V5, EM SCM, FM MAGo Performed on FM MEP, EM V1234, EM V5, EM SCM, FM MAGo, FM MAGi Very similar results 150 kHz picket fences

CE07 Performed on EM MEP, EM V1234, EM V5, EM SCM, EM MAGo Performed in lab (not screen room) 150kHz spikes

CS01 A dangerous test Performed on FM MEP, EM V1234, EM V5, EM SCM, FM MAGo, FM MAGi Resulted in overvoltage damage on MEP LNPS1 Resumed with EM MEP Performed on EM MEP, EM V1234, EM V5, EM SCM, EM MAGo Performed in lab (not screen room) No issues

CS02 Another dangerous test CS02 requires running from 50kHz to 400MHz Waiver to run only to 30MHz (test equipment limit) Deviation previously granted another instrument Performed on EM MEP, EM V1234, EM V5, EM SCM, EM MAGo Performed in lab (not screen room) No issues

CS06 Another slightly dangerous test Performed on EM MEP, EM V1234, EM V5, EM SCM, EM MAGo Performed in lab (not screen room) Rented pulse generator failed to make pulses To be continued in late April on EM

RE01 Emission lines generally at 150kHz picket fence Magnetic Performed on FM MEP, EM V1234, EM V5, EM SCM, FM MAGo, FM MAGi EM harnessing In UCB screen room Emission lines generally at 150kHz picket fence

RE01 - setup

RE01 – MEP side

RE01 – from above

RE01 – V1234

RE01 - MAGs

RE02 Emission lines generally at 150kHz picket fence Electric Performed on FM MEP, EM V1234, EM V5, EM SCM, FM MAGo, FM MAGi V1234 whip simulators EM harnessing In UCB screen room Emission lines generally at 150kHz picket fence

RE02 – Whip Simulators

RE02 - Monopole

RE02 - Biconic

RE02 - MF

RE02 - HF

RS03 Done on FM at APL Operational and Non-operational radiated susceptibility No problems