Use of the PIC simulation enables us to estimate the bounds on use of a noninteracting limit. In Fig. 6 we show the sheath dimension normalized to Debye length as a function of conductor voltage for angle of attack of 90°. For voltages up to the maximum considered the sheath does not overlap all the dielectric. For a Debye length of 0.47 cm corresponding to low earth orbit conditions, the sheath size at — 480 V would be 7.0 cm. Hence for the present large cell size 32 cm by 32 cm, the noninteracting assumption would be valid. For a typical scale 8 cm X 8 cm, the noninteracting assumption is valid as shown in Fig. 3. In Fig. 7 the minimum angle of attack allowed for the noninteracting limit to be valid as a function of conductor voltage is shown. This angle is obtained at a given voltage by calculating from the PIC simulations the minimum angle at which ions can approach the dielectric and only pass through the sheath of that conductor. As can be seen from the figure as the voltage and hence sheath increases the range of allowable angles of attack decrease. Figure 8 contains the drag coefficient as a function of voltage for /?= —90. The numerical results of Kuninaka & Kuriki are shown along with the PIC code results. For comparison the analytic results are shown for the cases ac= 1 which corresponds to
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