Instantaneous triple-probe method for the direct display of plasma parameters in a spacecraft condition

Abstract

It is proposed that the instantaneous triple-probe method can be applied to the direct display of parameters; particularly in the case of probe application during measurements carried out from spacecraft. The theory of the triple-probe method has been extended for the very high speed flowing collisionless plasma condition, i.e. in which the spacecraft speed U ≈ the most probable electron thermal velocity 〈 v e 〉 > the most probable ion thermal velocity 〈 v i 〉. This condition is particularly important both in the case of re-entry of spacecraft and in the solar wind plasma. Experiments have been conducted in a free molecular beam plasma chamber for S i = U 〈v i〉 > 10 . The experimental results and their relationship to the appropriate theory are presented.