Electron beam characterization of a compact far-infrared free electron laser
- Stanford Univ., CA (United States)
- China Academy of Engineering Physics, Chengdu (China)
- Stanford Univ., CA (United States). Dept. of Applied Physics
A compact, far-infrared free-electron laser (FIR-FEL) is operating at 85{micro}m at Stanford University, where the electron beam is obtained from a 1{1/2} cell, thermionic RF (2.856 GHz) cavity gun. This gun was not designed for FEL operation, and under the condition at which it was intended to operate, with a peak acceleration gradient below 85 MV/m, it would not be suitable. The authors have explored new parameter ranges, and have found that at high peak gradients, from 100--140 MV/m, the gun will function satisfactorily as an FEL accelerator. For example, thirty-nine percent of the total gun current was transmitted through a 1% energy window at a beam energy of {gamma} = 9.72. At {gamma} = 9.56, a 304 mA macropulse current with an estimated rms micropulse length of 3.4 ps was obtained, and the normalized rms emittance was measured to be 11.6 {pi}-mm-mrad for the 1% energy-spread electrons, corresponding to a beam brightness of 2.3 {times} 10{sup 11} A/m{sup 2}. For these parameters, the calculated small small-signal gain for the 0.5 m-long wiggler is 110% at a wavelength of 85 {micro}m. In this paper the authors characterize the electron beam from a 1{1/2} cell, thermionic cathode, RF cavity gun in a parameter range where it can be used as the accelerator for a far infrared FEL.
- OSTI ID:
- 137056
- Journal Information:
- IEEE Journal of Quantum Electronics, Vol. 31, Issue 9; Other Information: PBD: Sep 1995
- Country of Publication:
- United States
- Language:
- English
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