Abstract: One or more beam channels through which laser beams are directed, via one or more lasers, onto material of a sample in a sample chamber, are placed in a sample body. The laser beams generate a plasma in the material of the sample and directly or indirectly trigger reactions in the atomic nucleus or the electron shell. These reactions lead to a nuclear fission or fusion or to the generation of gamma rays or neutrons. Furthermore, gamma rays or neutrons can be conveyed to the sample body or to the beam channels, in order to trigger the same reactions. Discs can prevent or delay thermal energy or plasma from escaping in the beam channels. A positive or negative voltage U can be applied to the sample body or to electrodes situated within it, in order to suck up or convey electrons and favour the desired reactions. The sample body may be wholly or partially transparent, in order to adjust the focal points of the laser beams onto the material of the sample.