A 33 GHz free electron laser amplifier with reversed axial guide magnetic field
This thesis reports on a new regime of free electron laser operation using a helical wiggler field and a reversed axial guide magnetic field. The orientation of the axial field is such as to oppose the electron rotation imparted by the helical field. The 33 GHz free electron laser amplifier is driven by a mildly relativistic electron beam (750 kV, 300 A, 30 ns) and generates 61 MW of radiation with a 27% conversion efficiency. The results are compared with those obtained when the axial guide field is in its conventional orientation, where considerable loss of power and efficiency is observed. In addition to the above, the author has observed the following three phenomena. In the Reversed Field configuration the author has uncovered the presence of an anti-resonance associated with the motion of off-axis electrons in an electron beam of finite radius. Secondly, in the conventional orientation of the magnetic field, the author has found an unexpected shift in the radiation frequency relative to the input magnetron frequency. And thirdly, a comparison of the experiment with numerical simulations carried out the conventional regime shows that the observed nonlinear saturation is strongly dependent on the particle loss induced by the intense RF fields generated by the FEL interaction.
- Research Organization:
- Massachusetts Inst. of Tech., Cambridge, MA (United States)
- OSTI ID:
- 6982374
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Experimental study of a 33. 3-GHz free-electron-laser amplifier with a reversed axial guide magnetic field
Measurements of the temporal and spatial phase variations of a 33 GHz pulsed free electron laser amplifier and application to high gradient RF acceleration