Zee Media Bureau
Moscow: Aircrafts that are propelled by beams of light rather than conventional fuels is what the scientist and science fiction writers have always dreamt of.
Scientists say that for improving the thrust generated by laser-propulsion systems, new method may bring them one step closer to practical use.
Physicists Yuri Rezunkov of the Institute of Optoelectronic Instrument Engineering, Russia and Alexander Schmidt of the Ioffe Physical Technical Institute in Saint Petersburg, together have discovered a method which has been described in The Optical Society's (OSA) journal Applied Optics.
Currently, the amount of fuel the spacecraft can carry limits the maximum speed. Researchers have said that achieving higher speed means that more fuel must be burned — fuel that has to be carried by the craft. These burdensome loads can be reduced, however, if a laser — located at a remote distance and not on the spacecraft — were used to provide additional propulsive force. A number of systems have been proposed that can produce such laser propulsion.
One of the most promising systems involves a process called laser ablation, in which a pulsed laser beam strikes a surface, heats it up, and burns off material to create a plasma plume — a column of charged particles that flow off the surface.
Rezunkov and Schmidt describe the new method that integrates a laser-ablation propulsion system with the gas blasting nozzles of a spacecraft. The researchers found out that combining the two systems can increase the speed of the gas flow out of the system to supersonic speed while reducing the amount of burned fuel.
The researchers show that the effectiveness of current laser-propulsion techniques is limited by instability of supersonic gases, as they flow through the gas nozzle, as well as production of shock waves that "choke" the nozzle. But those effects can be reduced with the help of a laser-ablation plasma plume. Coupling ablation jet with supersonic gas flow through the nozzle, they found, significantly improves the overall thrust. "These techniques can be used not only for launching small satellites but also for additional acceleration of supersonic aircrafts to achieve Mach 10 and more," Rezunkov said.
(With Agency inputs)