Laser ion acceleration uses intense laser flashes to heat electrons of a solid to enormous temperatures and propel these charged particles to extreme speeds. These have recently gained traction for applications in selectively destroying cancerous tumor cells, in processing semiconductor materials, and due to their excellent properties for imaging and fusion-relevant conditions.
Massive laser systems with several joules of light energy are needed to irradiate solids for the purpose. This produces a flash of ions which are accelerated to extreme speeds. Thus, emulating large million-volt accelerators is possible within the thickness of a hair strand.
Such lasers are typically limited to a few flashes per second to prevent overheating and damage to laser components. Thus, laser-driven ion accelerators are limited to demonstrative applications in large experimental facilities. This is far from real-world applications, where the flashes of high-velocity ions are ideally available much more frequently.
Small lasers supplying several thousand flashes are routinely present in small university laboratories, operating at a thousandth of a joule of laser pulse energy.
Known mechanisms of laser-driven ion acceleration would predict that ion acceleration by a few kilovolts is possible in these conditions. This is far below the MeV range of ions driven by large-scale lasers. This trade-off poses a fundamental challenge in developing ion sources with a high rate of repetition.
In a study published in Physical Review Research, S.V. Rahul and Ratul Sabui from TIFR Hyderabad, led by Prof. M Krishnamurthy, have bridged this gap by producing megavolt energy protons using a few millijoule lasers, repeating a thousand times a second.
To read more, click here.