Laser-Driven Chip Points To Mini Particle Accelerator

In coverage of a handheld atomic force microscope called the ezAFM in April, C&EN commented, “What’s next? An ezParticleAccelerator?” The question may not have been too far-fetched because Robert L. Byer of Stanford University and coworkers have now demonstrated a laser-driven microchip that could lead to a miniaturized particle accelerator (Nature 2013, DOI: 10.1038/nature12664). Such instruments could be accessible and inexpensive sources of attosecond tunable X-rays for medical diagnostics, biological and materials research, and industrial processing. Current accelerators use radio frequencies to speed up atomic particles and are among the largest and most expensive scientific facilities worldwide. Laser-based accelerators could be smaller and less expensive, but nobody had been able to demonstrate laser-induced particle acceleration in a microscale device. Now, the Stanford-based group has shown that pulsed infrared laser light can boost the speed of preaccelerated electrons in ridge-patterned micrometer-sized channels in silicon-based microchips. The laser acceleration is 10 times as high as that achieved by Stanford’s conventional SLAC accelerator. When optimized, such a laser system could match the accelerating power of SLAC’s 2-mile path in only about 100 feet, the researchers estimate.