4 We build up a mass-driver first by adding in many more coils to make a complete "phase," as shown roughly to scale in my sketch at the right. They are spaced apart just far enough so that R ; 0 ( f A A 't It ll II ., '• ,, ,, shortly after the current in one coil has come back down to zero, the current in the next coil starts up. We do that in order to supply the current for all the coils ' ! J t I I ' 1 I '..i..__ I --r,--- .-,---,~9' .. i-- ' I I I 1 1 2>R.\Yi of one phase from one source, sequentially. That source is a capacitor, a set of plates on which we can store an electric I ' t ' ' t c.o I LS I I I 1 1 eF 0 NI ' ! I ' I ' Cl 0 tj tJ PHASE charge. Between every pair of pulses we have to replenish the charge on the capacitor. That has to happen rather quickly: even for the model now under construction in our joint Princeton/M.I.T. project, we have to turn on currents of thousands of amperes, for times of less than a hundred millionths of a second, to restore the charge on the capacitor before it is time for the pulse into the next drive coil. In a full-scale mass-driver used on the Moon or in space, the recharging current is supplied from an array of sol ar cell s. The drive coils of one phase form a long, straight tunnel through which the bucket flies. We further complicate the mass-driver by adding now a second set of coils, ca11 ed the "Phase 2" coi 1s, interleaved with those of Phase #1. They provide a maximum forward push just in the places where the push from the Phase #1 coils goes to zero, in between its current pulses. The Phase #2 coils are supplied by their own capacitor. When the bucket, under the action of all the coils of both phases, reaches its full velocity, we apply to it a slight braking force, so that it disengages from the payload, which continues forward under its own momentum. C.UA.Yel> sec.-ne/til (AM•LI EJCAGGQ'lA,..1>) The bucket is then guided (by the forces of magnetic flight) PA YL~A> around a s1i ght curve, and enters the decelerator. Because of the curve, the straight line of the decelerator diverges slightly from the line of the payload as it leaves the mass-driver. The decelerator is almost identical to the accelerator. The difference is that in the decelerator the currents are all reversed, so that the bucket is slowed down. In the decelerator, the capacitor is actually charged rather than discharged by the passage of the bucket. The decelerator is a generator, \-Jhile the accelerator is a motor. The decelerator takes energy out of the forward motion of the bucket
RkJQdWJsaXNoZXIy MTU5NjU0Mg==