|
|
|
| Current Issue |
|
|
| Resources |
|
|
|
Harnessing Artificial Lightning
| Article
# : |
18844 |
|
|
Section : |
NATURAL SCIENCE
|
| Issue
Date : |
12 / 1991 |
2,289 Words |
| Author
: |
Salvador L. Camacho
Salvador L. Camacho is vice president of research and
development for Plasma Energy Corporation of Raleigh, North
Carolina. He is the inventor of the PEC plasma torch and has
worked with plasma heating technology since 1961, including
eight years with the NASA space program. |
In the late 1960s the United States successfully landed astronauts on the moon and returned them safely to earth. This would not have been possible without the application of a little-known technology called plasma heating, which enabled NASA scientists and engineers to confirm the effectiveness of spacecraft heat shields.
NASA researchers knew well the processes by which a log or natural gas burns, and they also understood the source of heat in an electric light bulb. Yet neither by burning materials nor by flowing electric currents through them could the researchers achieve temperatures as high as those attained by a spacecraft reentering the earth's atmosphere. Resistive heating by passing an electric current trhough a metal seemed promising, but as the current flow was increased, the wire would melt or vaporize before it reached the desired temperature.
When NASA researchers finally did achieve reentry temperatures in the laboratory, they were using electric current to heat a material that was neither solid, liquid or gas: it was a plasma, matter in its fourth state. Plasma behaves very differently from matter as most people, scientists and engineers included, know of it. [see "Space Plasmas," THE WORLD & I, March 1988].
Although the composition of the universe as a whole is more than 99 percent plasma because the millions of billions of stars are all giant plasma balls, the composition of the earth and its atmosphere is almost exclusively non-plasma, that is, solid, liquid or gas. Familiar examples of plasma phenomena include lightning, the aurora borealis [see "The Polar Crowns," THE WORLD & I, August 1988], fluorescent lights, and electric sparks. A gas is converted to a plasma state whenever sufficient energy is invested in the gas to cause some of its atoms to lose an electron so that free electrons coexist with ions (changed atoms). On earth, taking lighting as a representative plasma phenomena, the voltage build-up between the cloud and the ground finally becomes so great that a plasma arc column carrying a massive electrical current between the ground and the cloud is formed. Just as the current flow through the filament in a light bulb produces heat and light due to the resistance of the filament, the current flow through the ionized air produces heat and light due to resistance of the plasma arc column to current flow.
The potential of current-carrying plasma as a heat source is well attested by the powerful clap of thunder produced at the place in the air where a lighting bolt breaks, releasing a powerful
...
Read Full Article
Look for this article in Ask.com
|
|
