Projectile distribution, color-coded for theoretical charge production using the relation . Note the strong dependence of speed and mass.
Impact targets used in the experiment.
Sensor configuration within the test chamber.
Photos of the plasma sensors in the chamber, from top to bottom: (a)RPAs, (b) FPA-theta, and (c) FPA-range.
Simultaneous measurements from a single impact of a 3.9 fg projectile on −1 kV tungsten at 35.3 km/s.
(a) Parameters in the SPM model. (b) Initial speed distribution causes the measured current peak to spread out.
(a) Geometry of plasma expansion cone and initial shape of discretized plasma shells. (b) Spherical cap geometry and internal electric field.
Measurement of six ion species from a 3.4 fg projectile traveling 35.2 km/s impacting tungsten biased at +1000 V, with SPM output.
Impacts on tungsten target. The red trace is from the RPA placed 85 mm from the impact point, and the blue trace is from the RPA placed 65 mm from the impact point. Left to right: same impact as in Figure 8 ; 0 V target with a 2.3 fg projectile impacting at 45.3 km/s; −1000 V target with a 27 fg projectile impacting at 3.5 km/s.
A 4.55 km/s impact of a 5.6 pg projectile on −300 V tungsten. The negative ion signal is indicated by the orange arrows.
Impacts on the −300 V spacecraft targets. The presence of negative ions is highly dependent on target material. The projectile masses are: (a) 0.59, (b) 6.9, (c) 13, (d) 7.6, and (e) 6.7 fg, respectively. The impact speeds are (a)59.2, (b) 18.7, (c) 21.6, (d) 18.3, and (e) 19.4 km/s, respectively.
Fractional composition of impact plasma from tungsten impacts as a function of impact speed.
Overlaid RPA measurements of impact plasma composition as a function of impact speed for (a) +1000 V tungsten, (b) +100 V uncoated solar cell, and (c) +100 V conductive OSR, color-coded for impact speed.
(a) Simulation with composition and temperature computed by SPM model. (b) Same composition with temperatures reduced by factor of 10.
Summary of impact measurements on the materials discussed in this paper.
Article metrics loading...
Full text loading...