Intense Laser Light Creates Optical Rocket


Researchers from University of Nebraska-Lincoln demonstrated the application of intense light that boosts electrons to their highest attainable speeds

A research led by Donald Umstadter, professor of Physics at the University of Nebraska-Lincoln, accelerated plasma electrons in the paths of intense laser light pulses that was close to the speed of light. According to the researchers the new application might be called an ‘optical rocket’ owing to the tremendous amount of force that light exerted in the experiment. The electrons experienced a force of around a trillion-trillion-times greater as compared to an astronaut launched into space. The novel application of intense light can improve the performance of compact electron accelerators. Moreover, such force can be for direct acceleration of matter.

A light with normal intensity exerts a tiny force whenever it reflects, scatters or is absorbed. A light sail is one of the several proposed application of such force and it could be used to propel spacecraft. However, the light force exerted in this experiment is exceedingly small and it would require years for the spacecraft to reach high speed. Light has an intensity gradient that can generate another type of force, which can be applied as an ‘optical tweezers’ that is used to manipulate microscopic objects. However, the force here is exceedingly small.

In the Nebraska experiment, the researchers focused laser pulses in plasma. The plasma waves were driven in the wakes of the pulses as electrons in the plasma were expelled from the paths of the light pulses by their gradient forces. Moreover, the electrons were allowed to catch the wakefield waves, which further accelerated the electrons to ultra-relativistic energy. The new application of intense light offers a method to control the initial phase of wakefield acceleration. Moreover, it improves the performance of a new generation of compact electron accelerators (CEA). These CEAs are expected to aid in development of a wide range of applications that were previously impractical owing to the enormous size of conventional accelerators.



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