• M.V. Vysotskyy, V.I. Vysotskii
  National Taras Shevchenko University of Kyiv, Radiophysical Faculty, Kiev

In the report the possibilities of FEL optimization and creation of tandem laser are considered. One of the optimal ways of coherent hard radiation generation is connected with the creation of FEL on channeling relativistic particles in perfect crystals [1]. The main role in solution of such problem plays the full Doppler effect [2]. The possibility of creation of tandem FEL, where one particle can radiate multiple times on one transition, is predicted for the first time. For such laser the intensive process of consecutive generation of two types of photons with different frequencies on the same radiating transition is possible and this double photon generation leads to the restoration of the initial state of quantum system. This effect allows to predict the possibility of multiple repeat of radiation cycle. The pumping source for such laser is the kinetic energy of moving particles. In such systems there is no need for inversion and absorption on radiation frequency is totally absent. The main problem of realization of tandem FEL is connected with the need of mediums with positive susceptibility in high frequency range, possible ways to solve this problem are also regarded.

1. Vysotskii V.I., Kuzmin R.N. Gamma-Ray Lasers, MSU Publ. House, Moscow, 1989.
2. Vysotskyy M.V., Vysotskii V.I. // Nuclear Instr. and Methods in Physics Research B, 2006, V. 252, P. 75-80

• M.V. Vysotskyy, V.I. Vysotskii
  National Taras Shevchenko University of Kyiv, Radiophysical Faculty, Kiev

The new type of oriental motion, so called parametric channeling of accelerated charged particles with internal energy structure in crystals or transversal focusing fields (TFF) is studied [*,**]. Peculiarities of this motion are connected with parametric coupling of transversal oscillations of fast particle in TFF (e.g. averaged field of crystal plains) and oscillations caused by internal processes in particle. Parametric channeling is investigated for small charged mesomolecules, atomic ions and nuclei with internal resonances, relativistic electrons. It was shown that such parametric coupling leads to the possibility of beam cooling and "collapse": critical decrease of transversal oscillations of moving structured ion in TFF due to energy transfer from this ion to its own internal electron (for atomic ion) or its internal low energy nuclear state (for fast nuclei). Also it was shown that parametric beam cooling with the decrease of transversal energy can take place at axial relativistic electron beams channeling. This process is caused by the parametric coupling between quantized channeling states and electron spin states in effective magnetic field in moving system.

* M.V.Vysotskyy V.I.Vysotskii, N.V.Maksuyta. Journal of Surface Investigation, V.2, No 2 (2008) 245.
** V.I.Vysotskii, M.V.Vysotskyy. Journal of Surface Investigation, 2008, V.2, No 2 (2008), 253.