6.23.2005

How would they weld the Starship Enterprise?

This article at American Scientist speculates how advanced plasma windows could serve electron-beam welding. A fun article, even the non-welding parts!

...Similar physical principles are behind a second Star Trek-like technology now coming into use, something called the "plasma window," which is the brainchild of Ady Hershcovitch, a physicist at Brookhaven National Laboratory. Hershcovitch conceived of the plasma window to serve in electron-beam welding, a technique used to fashion metal welds that are narrower and deeper than what can be accomplished with conventional tools.

The chief drawback of this technique is that the electrons used for welding must be accelerated in a vacuum (just like, for example, the electrons that light up the front of a television picture tube). Hence the objects being welded together must normally be placed within a sealed chamber from which the air has been extracted. With that constraint, one cannot make welds to, say, the deck of a battleship. Even for small work pieces, pumping down the vacuum chamber each time an object is inserted is time-consuming, making this form of welding rather costly.

To get around this difficulty, some have tried a variation of electron-beam welding that has the electrons accelerated in vacuum but the welding done at atmospheric pressure. Such systems rely on bulky, energy-hungry vacuum pumps to maintain the pressure differential between the source of electrons and the work piece. So they are awkward and costly to operate. What is more, the electron beam has a troubling tendency to spread out once it passes into the air, negating the fundamental advantage of electron-beam welding in the first place. Last May, Hershcovitch and colleagues at Acceleron, a company in Connecticut licensing his invention, described in the journal Physics of Plasmas how to sidestep these problems, making electron-beam welding that much more practical.

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