Figure 23 Shadowgraph of deuterium discharge taken in laser light. Turbulence of the plasma is clearly seen.
Westinghouse Electric Corporation scientists, on the other hand, have used the concentrated energy of the laser, not to look at, but to produce a plasma ([Figure 24]). They blasted an aluminum target the size of a pinhead with a laser beam, thereby vaporizing it and creating a plasma. The calculated temperature in the electrically charged gas was 3,000,000° centigrade. This is pretty hot, but still not hot enough for a thermonuclear reaction.
Figure 24 Plasma heating by laser light.
Diamagnetic loop Laser beam Vacuum chamber Magnetic field Magnetic coils Electrostatic probe Plasma Lens Mirror To vacuum pump Camera
The temperature of a plasma necessary to sustain a thermonuclear reaction is so high (above 10,000,000°C) that any material is vaporized instantly on coming into contact with it. The only means developed so far to contain the plasma is an intense magnetic field, or “magnetic bottle”; containment has been accomplished for only a few thousandths of a second at most. The objective of the Westinghouse research, which was supported by the Atomic Energy Commission, was to study in detail the interaction of the plasma with a magnetic field.
We do not have room to describe more applications in detail, but it may be interesting to list a few other uses of lasers—some commercial and some still experimental:
- Earthquake prediction.
- Measurement of “tides” in the earth’s crust under the sea.
- Laser gyroscopes.
- Highly accurate velocity measurement (useful in certain assembly line and continuous manufacturing processes).
- Scanner for analyzing photographs of bubble chamber tracks and astronomical phenomena.
- Computer output and storage systems; perhaps even complete optical data processing systems.
- Lightning-fast printing devices.
- High-speed photography ([Figure 25]).
- Missile tracking and accurate alignment of antennas.
- Automatic flaw spotter for big radio antennas.
- Aircraft landing aid for poor weather conditions.
- Fast, painless dental drill.
- Cancer research.
Figure 25 Twenty-two caliber bullet and its shock wave are photographed from the image produced by a doubly exposed laser hologram. The original hologram was exposed twice by a ruby laser within half a thousandth of a second as the bullet sped past at 2½ times the speed of sound.