[The U.S. Air Force has plans to improve radio communication over long distances by detonating plasma bombs in the upper atmosphere using a fleet of micro satellites.
It's not the first time we've tried to improve radio communication by tinkering with the ionosphere.
HAARP, the High Frequency Active Auroral Research Program in Alaska, stimulates the ionosphere with radiation from ground-based antennas to produce radio-reflecting plasma.]
Now the USAF wants to do this more efficiently, with tiny satellites -- such as CubeSats -- carrying large volumes of ionized gas directly into the ionosphere.
As well as increasing the range of radio signals, the USAF says it wants to smooth out the effects of solar winds, which can knock out GPS, and also investigate the possibility of blocking communication from enemy satellites.
[There are at least two major challenges.
One is building a plasma generator small enough to fit on a CubeSat -- roughly 10 centimeters cubed.
Then there's the problem of controlling exactly how the plasma will disperse once it is released.
The USAF has awarded three contracts to teams who are sketching out ways to tackle the approach.
The best proposal will be selected for a second phase in which plasma generators will be tested in vacuum chambers and exploratory space flights.]
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You know that they have already done experiments with plasma that go way beyond what is described above.
A plasma is a hot ionized gas consisting of approximately equal numbers of positively charged ions and negatively charged electrons.
The characteristics of plasmas are significantly different from those of ordinary neutral gases so that plasmas are considered a distinct "fourth state of matter."
For example, because plasmas are made up of electrically charged particles, they are strongly influenced by electric and magnetic fields while neutral gases are not.
An example of such influence is the trapping of energetic charged particles along geomagnetic field lines to form the Van Allen radiation belts.
In addition to externally imposed fields, such as the Earth's magnetic field or the interplanetary magnetic field, the plasma is acted upon by electric and magnetic fields created within the plasma itself through localized charge concentrations and electric currents that result from the differential motion of the ions and electrons.
The forces exerted by these fields on the charged particles that make up the plasma act over long distances and impart to the particles' behavior a coherent, collective quality that neutral gases do not display.
Despite the existence of localized charge concentrations and electric potentials, a plasma is electrically "quasi-neutral," because, in aggregate, there are approximately equal numbers of positively and negatively charged particles distributed so that their charges cancel.
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