Emissive probes for plasma potential measurements on the SERT II spacecraft

Development and flight history of the SERT II spacecraft

“…The probetot-space plasma potential difference was an electron sheath. The calculated sheath potential difference depended on probe emission current and plasma density, and varied between 0 V and -1 V 22. The probes were laboratory calibrated while immersed in a plasma and showed no detectable difference (+0.2 V) with a 8x 103/cm 3 to 6x 106/cm 3 change in plasma density or with a range of emission currents up to10 [aA.…”