It took every inch of the Large Hadron Collider's 17-mile length to accelerate particles to energies high enough to discover the Higgs boson. Now, imagine an accelerator that could do the same thing in, say, the length of a football field. Or less.
That is the promise of laser-plasma accelerators, which use lasers instead of high-power radio-frequency waves to energize electrons in very short distances. Scientists have grappled with building these devices for two decades, and a new theoretical study predicts that this may be easier than previously thought.
The authors are Carlo Benedetti, Carl Schroeder, Eric Esarey, and Wim Leemans, physicists at Lawrence Berkeley National Laboratory's Berkeley Lab Laser Accelerator (BELLA) Center. Their paper, "Plasma wakefields driven by an incoherent combination of laser pulses: A path towards high-average power laser-plasma accelerators," appears in the May Special Issue of Physics of Plasmas.
If their models prove correct, they could help lower the cost of high-energy physics research—the Large Hadron Collider cost $9 billion—as well as many other industrial and medical applications of accelerators.
Laser-plasma accelerators work by blasting a powerful laser beam into a plasma, a cloud of unattached electrons and ions.
"The effect is like the wake of boat speeding down a lake. If the wake was big enough, a surfer could ride it," Leemans, who heads the BELLA Center, explained. "Imagine that the plasma is the lake and the laser is the motorboat. When the laser plows through the plasma, the pressure created by its photons pushes the electrons out of the way. They wind up surfing the wake, or wakefield, created by the laser as it moves down the accelerator," he said.
The fast moving electrons leave the heavy ions behind. As they separate, they create gigantic electric fields, 100 to 1,000 times larger than those in conventional accelerators.