|For the first time ever: Protons accelerated in the plasma produced from hydrogen ice by a laser|
High-energy protons find application in medicine for irradiation of tumors as well as in many other science and technology fields
(such as proton radiography). Very efficient acceleration of protons occurs in the hot plasma produced by a high-power laser beam focused on a
target containing hydrogen. The thicker the target and the more hydrogen in it, the more accelerated protons.
The ideal would be to have a laser target of pure hydrogen frozen into a solid state at temperatures as low as -261°C.
Left: Ribbon of hydrogen ice. Right:Interferogram of the proton plasma (actual size about 2 mm by 2 mm).
The credit for this result belongs to the team of workers from the French laboratory INAC/SBT of the CEA, who developed for PALS a special helium
cryostat capable of producing a continuous ribbon of hydrogen ice, to ELI (Extreme Light Infrastructure) associates, who participated in preparation
of the cryostat and of measurements of accelerated protons and, of course, to the PALS team, which prepared and realized the experiment.
The cryostat (on the top). Two hundred fifty litres of liquid Helium were needed for this experiment.