3 ms·
A radar-shielding plasma shield sounds a bit like having a speaker wall to mask conversations.
by hengheng 10y ago
A radar-shielding plasma shield sounds a bit like having a speaker wall to mask conversations.
- jacquesm 10y agoWelcome to 'anti-sound': https://en.wikipedia.org/wiki/Active_noise_control https://en.wikipedia.org/wiki/Active_noise_control If the 'wail' is carefully tuned to the original forces dragging on the craft it might actually work.
- ridgeguy 10y agoMore like a sonic absorber. Plasmas are electrical conductors. The electric field of an incident radar wave couples to electrons and ions that compose the plasma and drives currents. This ends up dissipating the radar energy as heat. It's the same result as if the radar hit a poor electrical conductor like carbon-loaded plastic: not much reflection (cause of poor conductivity), but creation of internal currents that dissipate radar energy as heat. It's a resistive dummy load for the radar energy. This plasma-as-conductor thing can lead to some really interesting antennas. [1] Fill a long plastic tube with an easily ionized gas, and connect the output of your radio transmitter to it. When you want to transmit, ionize the gas column with a high voltage, low current discharge. Voila, you have a nice conductive column to radiate your RF from. Finished with transmission, switch off ionization power. Antenna is then electrically gone. Very important if you're on a battlefield, being hunted by things that can find antennas made out of metal. Your plasma antenna can be there and gone in a millisecond. Phased-array models exist, too. [1] https://en.wikipedia.org/wiki/Plasma_antenna https://en.wikipedia.org/wiki/Plasma_antenna