Astounding Science Fiction (British Edition), April 1944 — page 16: what you’re looking at

Machine-transcribed from the original scan — historical spelling and the odd misread are preserved.

14 field keeps the little devils running in the same orbit. Shoot it with two-hundred- cycle current, and in the half cycle your electrons are made to run around the center a few million times. That builds up a terrific velocity—measured in six figures, believe it or ‘not. Then the current begins to level off at the top of the sine wave, and the magnet loses its increasing phase. The electrons, still in acceleration, begin to whirl outward. The current levels off for sure and begins to slide down—and the electrons roll off at a tangent to their course. This stream can be collected and used. In fact, we have a two-hundred- cycle beam of electrons at a couple of billion volts. That,’ brother, ain’t hay!” “Is that enough?” *“Nope.”’ “Then how do you hope to increase this velocity? If it is easier to run this up than it would be the cyclotron, how do we go about it?” Channing smiled and began to draw dia- grams on the tablecloth. Joe looked over with a worried frown, and then shrugged his shoulders. Diagrams or not, this was an emergency—and besides, he thought, I need another lesson in high-powered gadgetry. “The nice thing about this betatron,” said Channing, “is the fact that it can and does run both ends on the same supply. The current and voltage phases are correct so that we do not require two supplies which operate in a carefully balanced condition. The cyclotron is one of the other kinds; though the one supply is strictly D.C., the strength of the field must be controlled separately from the supply to the oscillator that runs the D plates, You’re sitting on a fence, juggling knobs dfid stuff all the time you are bombarding with acyc. _ “Now let us inspect the supply of the betatron. It is sinusoidal. There is the catch. There is the thing that makes it possible. that single fact makes it easy to step the power up to terrific quantities. Since the thing is fixed by nature so that the input is proportional—electron gun initial velocity versus magnetic field strength, if we increase the input voltage, the output voltage goes up without having to resort to manipulistic gymnastics on the part of the operator.” “Go on, Professor Maxwell.” “Don’t make fun of a great man’s name,” said Arden. “If it wasn’t for Clerk Maxwell, we'd still be yelling out of the window at one another instead of squirting radio beams all over the Solar System.” ASTOUNDING SCIENCE-FICTION “Then make him quit calling me Tom Swift.” “Go on, Don, Walt and I will finish this argument after we finish Hellion Murdoch. “May 1?” asked Channing with a smile. He did not mind the interruption; he was used to it in the first place and he had been busy with his pencil in the second place. ““Now look, Walt, what happens when you smack a charged condenser across an inductance?” “You generate a damped cycle of the amplitude of the charge on the condenser, and of frequency equal to the L, C, con- stants of the condenser and inductance. The amplitude decays according to the factor Q, following the equation for decrement—” “Never mind, I’ve got it here on my whiteboard,” smiled Channing, pointing to the tablecloth. “You are right. And the purity of the wave?” “Sinusoidal... hey! That’s it!” Walt jumped to his feet and went to the telephone. “What’s ‘it??”? asked Arden. “The betatron we have runs off of a five- hundred-volt supply,” chuckled Channing. “We can crank that up ten to one without running into any difficulty at all. Five- - hundred-volt insulation is peanuts, and the stuff they put on wires nowadays is always good for ten times that just because it wouldn’t be economical to try to thin the insulation down so that it only protects five hundred. Pll bet a bat that he would crank the input up to fifty thousand volts without too much sputtering—though I wouldn’t know where to lay my lunch hooks on a fifty-thousand-volt condenser of any appre- ciable capacity. Well, stepping up the rig ten to one will dish us out just shy of a couple of thousand million volts, which, as brother Franks says, is not hay!” Walt returned after a minute and said: “Warren’s measuring the inductance of the betatron magnet. He’ll calculate the value of -C required to tune the thing to the right frequency and start to achieve that capacity by mazing up whatever high-voltage con- densers we have on the Station. Now, Don, let’s calculate how we’re going to make the thing mobile.” “That’s a horse of a different color. We’ll have to use electro-magnetic deflection. From the constants of the electron stream out of our souped-up Suzy, we'll have to compute the necessary field to deflect such a beam. That'll be terrific, because the elec- trons are hitting it up at a velocity ap- proaching that of light—maybe a hundred comiclooks (©