densities would be 10 or more orders of magnitude higher than for comsats. and this is expected to cause much more pronounced effects in the areas of plasma heating and non-linear scattering. When coupled with the need to maintain constant, high-precision pointing of the beam on the rectenna, understanding space plasma interactions is considered very important. Indeed, the Japanese METS experiment has proposed focusing a microwave beam into a tight region just above the transmitting antenna in order to achieve the highest possible energy density. The plasma interactions are then measured by way of a probe inserted into this region as shown in Figure 4.1-1. (See also Section 7.2) Plasma interactions are also important to determine for the reconversion of the microwave beam into electricity at the rectenna. Understanding this and other interactions is one of the primary reasons for the Texas A&M Center for Space Power experiment on the Space Shuttle. CSP state that, [26] The mission scenario will be to vary the microwave power level and observe the transient and steady-state response of the system, as well as the leakage current through the plasma in a specific orbit. The attitude of the rectenna with respect to the plasma stream could be changed to establish the effects of the plasma. Other important factors to study are the interference effects of side-lobes on terrestrial and space-based communications systems and the effects of atmospheric drag on large rectennas. 4.2 Operational Considerations In addition to understanding pointing and other power transmission phenomena, it is also important to demonstrate the functional aspects of the system as a whole. Ideally, it would be advantageous to be able to undertake an initial demonstrator as a “subscale” test of the larger Powersat. This might seem
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