Patent EA-004665-B1 (EA)
Title: A process for generating electromagnetic radiation and volume free electron laser apparatus for carrying out the process
IPC: H01J25/00
Filed: 2001-12-25
Abstract: 1. A process for generating electromagnetic radiation comprising the spatially-modulated electrodynamic structure and electron beam shaping and guiding (3) with respect to said electrodynamic structure, characterized in that comprising orienting said spatially-modulated electrodynamic system with respect to the velocity of a beam of electrons to provide coupling of orientation and spatial periodicity by conditions of synchronism and multiwave diffraction, according to the expressions as follows: where omega is the frequency of said electromagnetic radiation, is the wave vector of said electromagnetic radiation, is the velocity of the electron beam, are the reciprocal lattice vectors defined by the grating orientation and structure, is the set of the reciprocal lattice vectors, d1, d2, d3 are the periods of the spatially periodic grating, ki, li, mi are the integer numbers, i=1, ..., s+1, where s+1 is the number of waves participating in diffraction process, Omega is the frequency of the oscillatory motion of an electron in an external field, moreover if the external field absent then Omega=0, here the said spatially-modulated electrodynamic structure is oriented to provide conditions of the s-times degeneration of the diffraction roots with the following dependence of the imaginary part of the solution of the dispersion equation on the density of the electron beam: , where omegaL is the Langmuir frequency of the electron beam, gs is the coefficient of the electromagnetic wave coupling with the electron beam. 2. A process as recited in claim 1, characterized in that comprising guiding at least two electron beams with respect to said electrodynamic structure, said electron beams mainly propagate parallel and/or concentric to each other. 3. A process as recited in either claim 1 or claim 2, characterized in that comprising creating at least one guiding channel of the specified cross-section for electron beam guiding. 4. A process as recited in either claim 1 or claim 2 characterized in that comprising creating in said electrodynamic structure at least two periods of modulation, wherein one of the modulation periods is dedicated for radiation excitation, while the other modulation period provides distributed feedback in said electrodynamic structure. 5. A process as recited in any claim from 1 to 4, characterized in that comprising alteration of the specified orientation of electrodynamic structure with respect to the velocity of said electron beam during generation process providing possibility of radiation frequency tuning due to alteration of the geometric position of electrodynamic structure. 6. A process as recited in any claim from 1 to 5, characterized in that comprising additional modulation of electrodynamic properties of said structure that is made by the specified manner spatially and with time. 7. A process as recited in any claim from 1 to 6, characterized in that comprising realizing interaction of the electrodynamic structure, having at least two modulation periods, with an electron beam during generation process. Interaction for one of the modulation periods excites electromagnetic pumping wave (the dynamical wiggler) interacting with the electron beam, while interaction with the modulation structure G having another period that is mainly shorter then former in conditions of the multiwave diffraction provides generation of radiation with the wavelength shorter then the first modulation period. 8. A process as recited in any claim from 1 to 7, characterized in that having the improvement comprising of creation electrodynamic structure as a set of periodically placed separate elements providing necessary electrodynamic properties for the structure. 9. A process as recited in any claim from 1 to 8, characterized in that comprising using a diffraction grating as at least one element of said structure. 10. A process as recited in any claim from 1 to 9, characterized in that comprising using a magnetostatic wiggler as at least one element of said structure. 11. A process as recited in any claim from 1 to 9, characterized in that comprising using an electrostatic wiggler as at least one element of said structure. 12. A process as recited in any claim from 1 to 11, characterized in that comprising rotation the velocity of said electron beam with respect to the specified spatial position of said structure. 13. A process as recited in any claim from 1 to 12, characterized in that comprising entering into electrodynamic structure the electromagnetic signal with carrier frequency according to claim 1. 14. Volume free electron laser apparatus comprising the spatially-modulated electrodynamic structure, a source of a beam of electrons, directing apparatus providing to guide electron beam, characterized in that comprising the presence of instrument for altering of electrodynamic structure orientation with respect to the electron beam velocity as well as electrodynamic structure periodicity in correspondence with the condition of maximality of instability increment that is the solution of the equation: where omega is the frequency of the radiated wave, is the wave vector of said electromagnetic radiation, is the velocity of the electron beam, omegaL is the Langmuir frequency of the electron beam, g is the coefficient of the electromagnetic wave coupling with the electron beam, D is the dispersion equation coupling the frequency omega and the wave vector in the electrodynamic structure in the absence of the electron beam, = + , are the reciprocal lattice vectors defined by the grating orientation and structure, is the set of the reciprocal lattice vectors, d1, d2, d3 are the periods of the spatially periodic grating, ki, li, mi are the integer numbers, i = 1, ..., s+1, where s+1 is the number of waves participating in diffraction process, Omega is the frequency of the oscillatory motion of an electron in an external field (if the external field absent then Omega = 0). 15. Volume free electron laser apparatus according to claim 14, characterized in that comprising the presence of instrument providing alteration of the specified orientation of electrodynamic structure with respect to the electron beam during generation process with possibility of radiation frequency tuning due to alteration of the geometric position of electrodynamic structure. 16. Volume free electron laser apparatus according to either claim 14 or 15, characterized in that having comprising the presence of at least two sources of electron beam with possibility of creation spatially separated electron beams, said electron beams mainly propagate parallel and/or concentric to each other. 17. Volume free electron laser apparatus according to any of claims 14-16, characterized in comprising using the electrodynamic structure with at least one guiding channel of the specified cross-section for electron beam guiding. 18. Volume free electron laser apparatus according to any of claims 14-17, characterized in that comprising using the electrodynamic structure with at least two periods of modulation, wherein one of the modulation periods is dedicated for radiation excitation, while the other modulation periods provide possibility for creation distributed feedback in said electrodynamic structure. 19. Volume free electron laser apparatus according to any of claims 14-18, characterized in that comprising using the electrodynamic structure, having at least two periods of spatial modulation of electromagnetic properties having different reciprocal lattice vectors, so that the first spatially modulation structure interacting with the electron beam creates electromagnetic pumping wave (with possibility of the dynamical wiggler creation), while the other modulation structure G provides resonance conditions of synchronism and diffraction of radiation with the wavelength shorter then the first modulation period. 20. Volume free electron laser apparatus according to any of claims 14-19, characterized in that comprising making the electrodynamic structure from the dielectric material. 21. Volume free electron laser apparatus according to any of claims 14-19, characterized in that comprising making the whole electrodynamic structure from the current-conducting material. 22. Volume free electron laser apparatus according to any of claims 14-19, characterized in that comprising making the whole electrodynamic structure from the semi-conducting material. 23. Volume free electron laser apparatus according to any of claims 14-19, characterized in that comprising making the whole electrodynamic structure from the composit material on the base of dielectrics and/or current-conductors and/or semi-conductors. 24. Volume free electron laser apparatus according to any of claims 14-23, characterized in that comprising making the electrodynamic structure as a set of periodically placed separate elements. 25. Volume free electron laser apparatus according to any of claims 14-24, characterized in that comprising making the electrodynamic structure as a set of concentrically placed separate elements. 26. Volume free electron laser apparatus according to any of claims 14-25, characterized in that comprising making a diffraction grating as at least one element of said electrodynamic structure. 27. Volume free electron laser apparatus according to any of claims 14-26, characterized in that comprising making a magnetostatic wiggler as at least one element of said structure. 28. Volume free electron laser apparatus according to any of claims 14-26, characterized in that comprising making an electrostatic wiggler as at least one element of said structure. 29. Volume free electron laser apparatus according to any of claims 14-28, characterized in that comprising providing said directing apparatus providing to guide electron beam with the instrument for rotation of velocity of said electron beam with respect to the specified spatial position of said structure. 30. Volume free electron laser a