Megawatt Class Free Electron Lasers for Naval Application - Short Rayleigh Length and Stability Analysis
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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The free electron laser FEL is theoretically capable of scaling up to a MW class laser for naval point defense. At such high power levels, the FELs optics could be damaged. An FEL operating with a short Rayleigh length reduces intensity at the mirrors however, the performance of short Rayleigh length FELs is unknown. This thesis presents simulations of Thomas Jefferson Laboratories proposed 100 kW FEL operating with a short Rayleigh length, and of a proposed 1 MW FEL undergoing shipboard induced mirror vibrations. In the 100 kW FEL, Rayleigh lengths of 0.1L to 0.5L where L is the undulator length were simulated. Weak field gain increases as Rayleigh length decreases, indicating that short Rayleigh length FELs will start from spontaneous emissions. Final FEL efficiency also increases as Rayleigh length decreases, with the exception of a spike at the typical Rayleigh length design value of 0.3L. For the 1 MW FEL system, the high operating current acts to stabilize the optical mode against vibrations that result in mirror tilts of 0 to 400 microradians, where final output power was reduced 80. When used in conjunction with an active mirror alignment system, output power of the 1 MW FEL is unaffected.
- Lasers and Masers
- Directed Energy Weapons
- Defense Systems