Controlling proton beams through polarisation
Laser-driven proton beams can be controlled by adjusting the polarisation of the laser, according to a new Nature Communications paper from A-SAIL team members and their partners.
The paper builds on earlier work led by Paul McKenna and the Strathclyde team, which showed how a laser pulse striking an ultra-thin foil produces its own aperture – rather like the opening in a pin-hole camera – through which the laser passes, getting diffracted on the way.
In this new paper, the team demonstrates that by adjusting the polarisation of the laser, the resulting diffraction pattern can be manipulated, thus shaping the dynamics of the electrons emitted. As a result, crucially, the team has a mechanism for changing the profile of the resulting proton beam.
This could have significant implications for the aims of the A-SAIL Project, as control of the proton beams is important in paving the way towards eventual medical use of the technique.
The paper has already attracted some attention, being featured on Physicsworld.com, and being described as an “important contribution” by Victor Malka of ENTSA Paris-Tech. The research could have applications beyond the scope of the A-SAIL Project, with Paul McKenna suggesting it could help in producing “experimental models of astrophysical relativistic plasma jets created by a rotating black-hole accretion disc”.
Full details of the paper are as follows:
‘Towards optical polarization control of laser-driven proton acceleration in foils undergoing relativistic transparency’, Bruno Gonzalez-Izquierdo, Martin King, Ross J. Gray, Robbie Wilson, Rachel J. Dance, Haydn Powell, David A. Maclellan, John McCreadie, Nicholas M. H. Butler, Steve Hawkes, James S. Green, Chris D. Murphy, Luca C. Stockhausen, David C. Carroll, Nicola Booth, Graeme G. Scott, Marco Borghesi, David Neely & Paul McKenna, Nature Communications 7, Article number: 12891 (2016), doi:10.1038/ncomms12891 (Available here.)
See also ‘Laser polarization boosts quality of proton beams’, Tim Wogan, Physicsworld.com, September 20, 2016
5 October 2016