USA as Represented by Secretary of the Navy

United States of America as Represented by the Secretary of the Air Force

S Perry Schlesinger

Thomas C Marshall

Phillip A Sprangle

Victor L Granatstein

Arthur A Grossman

Robert K Parker

Philip C Efthimion

David B McDermott

Shien-Chi Chen

A free electron laser (FEL) is described which is used for generating high ower radiation in a region of increasing guiding magnetic field before injection into an undulating low magnetic field. It includes an electron beam propagating along a guiding magnetic field B.sub.0 (approximately 10 kilo gauss) inside a hollow metallic tube used as a wave guide. Around the path of the beam, an undulator in the form of a bifilar helical winding or the like produces a periodic magnetic field B.sub.1 (approximately 0.5 to 1.0 kG). The electron motion accordingly has a substantial transverse component and the motion at the cyclotron and undulator frequencies occurs. Due to the energy exchange between the gyrating component of electron motion and an electromagnetic wave already present in the hollow tube, radiation of a calculable frequency is amplified.

Free electron laser using a relativistic beam with spiralling electron

The generation of very high power pulses of coherent electromagnetic radiation that are continuously tunable in frequency is accomplished by means of a free electron laser in which a hollow relativistic electron beam is projected along the longitudinal axis of an evacuated drift tube. A first magnetic field expands the electron beam into an annular peripheral interaction region of the drift tube where the beam interacts with a second periodic radial magnetic field. Frequency is varied by changing the electron velocity of the electron beam or by changing the periodicity of the radial magnetic field. The device can be made to operate as an oscillator by the inclusion of resonant cavity defining mirrors within the interaction region, or as an amplifier by injecting a coherent radiation signal into the interaction region. Both oscillator and amplifier functions can be incorporated into a single device. Linewidth is narrowed by utilizing a Smith-Fox interferometer to couple the generated coherent radiation into an output light pipe.

Free electron laser employing an expanded hollow intense electron beam

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New York, NY, United States of America

S Perry Schlesinger