| 摘要 |
The invention relates to a method for generating electromagnetic radiation (preferably UV, VUV, XUV, or X-rays), to an optical short-period undulator (10) and to a free-electron laser comprising the latter. To accomplish the method, a high-energy electrically charged particle beam (5) is provided, and high-intensity electromagnetic pulses (7, 7a, 7b) are generated, and by interfering said pulses with one another an electromagnetic standing wave is created, wherein said standing wave has an electric field strength of a pre-determined peak value. The particle beam is directed through the non-steady electromagnetic field of the standing wave in or in the vicinity of a plane spanned by nodes with maximal electric field strength of said electromagnetic standing wave. Meanwhile, by the electromagnetic field of the standing wave, the particle beam is forced to travel along an undulating path and thereby, in the form of radiation emitted by said particle beam, electromagnetic radiation that propagates in the propagation direction of the particle beam is generated. Said short-period undulator (10) comprises a pulse source (2) to emit high-intensity pulses falling into the terahertz frequency range and an interaction region to direct a high-energy electrically charged particle beam, in particular an electron beam, through the undulator with undulator effect. The undulator effect is provided in the interaction region through a dynamic effect developing in or in the vicinity of a plane spanned by nodes with maximal electric field strength of an electromagnetic standing wave created by the interference of high-intensity pulses falling into the terahertz frequency range, emitted by said pulse source. |
