Scientists have created a method of accelerating ions, can improve cancer therapy

© Photo : ELI BeamlinesВакуумная camera for laser-plasma experimentsScientists have created a method of accelerating ions, can improve cancer therapy© Photo : ELI BeamlinesПодпишись to daily updates RIA Science

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The staff of the Institute of laser and plasma technologies, National research nuclear University «MEPhI», together with colleagues from Germany and the Czech Republic have proposed a new method for the generation of superstrong quasistatic electric fields that accelerate ions in a laser plasma. The results are of great importance for medicine, in particular proton therapy is a modern method of treatment of cancer. A scientific paper published in the prestigious scientific journal Scientific Reports.

As you know, there are three main methods of cancer treatment: surgery, chemotherapy and radiation (radiotherapy). The latter is a ionizing radiation, which is detrimental not only to tumor but also to the surrounding healthy tissue. This imposes a limitation on the power of the beam of gamma rays used in radiotherapy.

In this respect, it is much better to use protons. Due to the relatively large mass of protons experience only minor lateral scattering in tissue, and the variation of the length they run very small. Therefore, the proton beam can be very accurately focus on the tumor without damage to surrounding healthy tissue.

But in order to obtain beams of protons, you need a particle accelerator. It is a very expensive, multi-ton equipment. For example, the synchrocyclotron therapy centre in Orsay (France) has a total mass of 900 tons. Therefore, in many universities around the world are working on alternative methods of generation of ultra-fast beams of charged particles. One of them is based on using a laser accelerator.

Laser accelerators of charged particles significantly smaller and cheaper than conventional cyclotrons and synchrotrons, but the quality obtained with their help beams are still insufficient for most practical applications due to the large variation in the energies of protons and insufficient capacity. Today started a real race for the new techniques of laser acceleration: receiving proton beam with energy of 100-200МэВ and scatter not exceeding a few percent, would open a new era in laser medicine.

According to researchers at the University developed their theory can help in the development of new methods of laser acceleration. «We have predicted theoretically and demonstrated with numerical simulations is quite paradoxical at first glance: the radiative friction force acting on the charged particles that emit electromagnetic waves may contribute to the acceleration», – told associate Professor of the Department of theoretical nuclear physics, MEPI, and research fellow of the Institute of Extreme Light Infrastructure Beamlines (Czech Republic) Eugene Gelfer.

In mechanical systems friction forces always lead to the loss of kinetic energy and the attenuation of the ordered motion. The force of radiative friction is arranged in a special way – it occurs due to energy transfer of the external field (in this case a laser) into energy quanta of very high frequencies. Work body that makes that pumping is electron, and in the process of energy transfer from one tank to another, he can slow down and speed up.

«We considered the spread of intense laser pulse in plasma. In the electromagnetic fields of power and above petawatt (1 PW=1 015 W, for comparison, the capacity of the largest power stations world – 22 500 MW, which is about 50,000 times smaller) electrons radiate so intensely that their movement is determined not only by Lorentz force, but the force of radiation friction due to the recoil radiation. The latter may even exceed the Lorentz force magnitude. We have shown that the slower electrons of the radiation friction in the plane perpendicular to the direction of propagation of the laser beam, leads to a stronger acceleration of their forward. Thus contributing to a more effective charge separation in the plasma and increased, the resulting longitudinal electric field. It is this field causes the acceleration of ions, so the obtained results can help in obtaining ion beams of higher quality,» says Eugene Gelfer.