Proposal of an electromagnetic ondulator for free electron laser

This paper proposes an electromagnetic (EM) undulator with millimetric or sub-millimetric wavelength which could be used with free electron laser (FEL), able to operate under a self amplified spontaneous emission (SASE) regime, in a single passage of an electron beam through it. This has the advantage that it does not require an optical cavity which is difficult or even impossible to be formed in case of such smaller and smaller wavelengths of the coherent EM radiation. Moreover, when used as a FEL, operating under other regimes than SASE, the undulator length is relatively small. The paper presents the constructive solution and part of the main parameters. (Author)