The magnetic field prevented the acceleration of protons
A group of scientists from Russia, France and the United States discovered that when protons are accelerated by the laser the emerging magnetic field slows them down. The discovered phenomenon will complicate the development of compact laser technologies for medicine.
Laser proton acceleration is a promising technology for use in radiotherapy treatment of cancerous diseases. Protons act more selectively on cancer cells compared with the X-ray radiation commonly used for these purposes, and can significantly reduce the dose received by healthy tissues surrounding the tumour.
Scientists have tested the acceleration of protons by a laser at the LULI Centre in France and at Sandia National Labs, USA. Scientists expected proton energy of over 100 MeV, but it reached only 40 MeV. The value was that low due to ultra-high magnetic fields appearing in the target under the action of the laser, the scientists believe. The fields inhibit electrons and thus protons do not have enough energy.
The researchers plan to conduct similar research but with faster laser pulses at the Institute of Applied Physics of the Russian Academy of Sciences, where the laser complex PEARL was created and now functions. Preliminary calculations show that with fast pulses the negative effect of the magnetic field will be less significant.