V.K. Kramarenko, A.V. Panchenko, A.P. Mikhajlov, N.S. Knyazev, A.V. Pereverzeva, S.N. Gorbach, L.A. Makarevich, K.Ju. Taletsky, F.F. Kamenets, T.Zh. Esirkepov, S.V. Bulanov
The question on radiation losses in the charged particles motion attracts the attention of researchers in more than one hundred years. Radiation friction affects strongly on the dynamics of the plasma interacting with light starting from intensity over 1023 W/sm2. The ultrahigh intensity radiation with matter interaction processes with the radiation friction force (RF) taken into account has been discussed in various applications. There is persistent interest towards this problem.
On the basis of the code REMP, allowing to carry out a two–dimensional numerical simulation of the interaction of radiation with matter, has been implemented the method of accounting the effect of RF as a small correction to the Lorentz force. In this method, the first step of the Lorentz force is calculated, and the RF is entered as a small correction in the second step. Thus the action of Lorentz force and the RF are described by different numerical operators.
For comparison with known results we have carried out test experiments on ion acceleration in the radiation–dominant mode of interaction of a laser pulse with the foil of the supercritical concentration. And we have observed the coincidence with the results of other research groups. The results have showed that with accounting frictional force, as predicted in the article, volume occupied by the particles of the phase space compress and, as noted in the article, changes of the final energy of particles are small. Compression phase volume is explained the fact that RFF plays cooling mechanism that takes into account the emission of high–energy photons. These photons emerge freely from the plasma, taking with them some part of the energy, momentum and entropy. Also we compared the effect of RFF on the process of acceleration of the various particles.
Experiments were carried out with mass–limited targets. We studied the interaction of circularly polarized pulses with different forms of the envelope. Compression of the ion beam can be clearly seen in the diagrams of the particle distribution under the angle dispersion. Comparison of the results suggests a more efficient focusing of the ion beam. Decrease the effectiveness of the expansion increases the number of accelerated particles in the radiated zone. Thus, taking into account high–frequency component of RFF leads to a decrease in the efficiency of ion acceleration.