Gold could be the missing piece to increasing RPA efficiency
06 Feb 2023



As laser technology has developed over the past couple of decades, interest in laser-driven ion acceleration has increased. One promising mechanism of laser-driven ion acceleration is Radiation Pressure Acceleration (RPA).

Gloved hands holding a tiny gold foil using tweezers.

​This method of ion acceleration involves an ultra-intense laser, like Vulcan at the CLF, “pushing" a tiny portion of an ultra-thin target (~100 nm thick) forward. An advantage of this method is that it is a potentially more efficient ion acceleration mechanism compared to other techniques, capable of scaling to higher ion energies more favourably with increasing laser intensity.

However, an issue with RPA is that the ultra-thin target needs to stay intact as it is “pushed" by the laser, which becomes increasingly difficult the thinner the target is made. A team of researchers led by Queen's University Belfast, and supported by CLF staff, used the CLF's Vulcan Target Area Petawatt (TAP) to investigate if using a gold coating technique enables thinner targets to be used in RPA than would be possible without the coating. This is vital for efficient RPA, as you want to shoot the thinnest target possible while maintaining the process for as long as possible.

The research team demonstrated that adding this gold coating to the ultra-thin targets enabled the targets to be made thinner than before, while maintaining the target's integrity when the laser pulse was incident on them. Results like these pave the way for more efficient, tuneable ion acceleration in upcoming laser facilities, like EPAC.

The research also showed improved efficiency of generating beamed neutrons without the need for a secondary convertor. Typically, you make an ion beam, then direct it into a secondary target to convert it into a beam of neutrons. However, this research used deuterated targets and generated beamed neutrons without a secondary convertor. These results show that using deuterated targets could make it unnecessary to have a secondary target for a range of laser-accelerated neutron applications.

Read the publication to find out more.

Contact: Snelgrove, Kaylyn (STFC,RAL,CLF)