Scientific Assessment of Free-Electron Laser Technology for Naval Applications

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1 Scientific Assessment of Free-Electron Laser Technology for Naval Applications Fall Meeting of the Board on Physics and Astronomy November, 007 Beckman Center, Irvine, Calif.

2 Free-electron electron lasers Interest in free-electron lasers has blossomed in the past decade with advent of technical progress in production, transport, and stable operation of high average beam powers The military has long been interested in so-called directed-energy weapons Army has pursued solid-state lasers Air Force has pursued chemical lasers Navy has pursued free-electron lasers operating in the optical/near-ir regime Navy FEL program is concentrated at Jefferson Lab with annual budget of $10-0M per year

3 Proposed NRC study Proponents of FEL technology have been itching to propose a weaponization program that would seek > 1MW average power delivery to a remote target Office of Naval Research approached NRC in January 007 to discuss potential study Naval Studies Board and Board on Physics and Astronomy are collaborating in response Prospectus was developed and proposal was successful

4 Terms of Reference Review the current state-of-the-art and anticipated advances for highaverage-power free-electron lasers (FELs). Using performance characteristics defined by the Navy for directed-energy applications, analyze the capabilities, constraints, and tradeoffs for FELs. Evaluate the scientific and technical development path from current demonstrated capabilities toward the eventual goal of achieving megawatts of radiated power at wavelengths suited to naval applications; consider the realistic constraints of ship-board installation. Identify the highest priority scientific and technical gaps along the development path from present-day capabilities through a 100 kw test facility to a megawatt demonstration project. Recommend a phased approach for this development path using staged milestones with explicit performance and success criteria at each stage.

5 High average power FEL The Navy s pipe-dream is a compact, energyrecycling, high-average power, (superconducting), adaptive-optic, MW-class free-electron laser that will fit on board a ship Quite a challenge The device can be viewed in terms of four subsystems, all of which must be maximized and smoothly integrated Electron source and injectors Accelerator and wiggler/lasing mechanism Optical elements for storing the energy and then directing and releasing it Propagation and transport through the atmosphere of the marine environment

6 Power flow in a high-power FEL with energy recovery onvdq Bnmudqsdq Lnctk`snq CB onvdq 0/- L V 7 L V 1-0 L V Knv,kdudk QE Jkx.HN S Knv,kdudk QE Jkx.H NS - L V 0- L V Hmidbsnq LV 61 LV Rtodqbnmctbshmf@bbdkdq`snq Dkdbsqhbhsx QE Dkdbsqnmr K`rdq Khfgs EDK ad`l Vhffkdq L V Ctl o 6/- L V 61 L V 6

7 Technology Readiness Levels of FEL Sub-systems Now Optical Architecture Oscillator Conventional Short Rayleigh-length Amplifier Pinched beam Regenerative amplifier (?) Optics High reflective coatings Grazing incidence coatings Transmissive outcouplers (?) Ampere-class Injectors DC Gun Superconducting RF booster Normal-conducting RF injector Superconducting RF injector Photocathode & drive laser Ampere-class Superconducting RF Accelerator Elliptical, niobium Spoke, niobium Elliptical, magnesium diboride Advanced Technologies Compact, emittance-preserving bends MW inductive output tubes (IOT) 6 7

8 Observations Proposed committee will have the option to be cleared for access to classified information Only as deemed necessary by the committee Some committee members will need to know enough to know that the committee should know more Goal is to provide a scientific assessment of the S&T challenges to preparing a 100-kW device noting what bottlenecks will need to be addressed in pursuit of a MW-class facility DOE labs are increasingly pursuing this area Key players are Los Alamos, Jefferson Lab, Argonne, and Brookhaven Proponents and skeptics have very different views This study can add significant value if it provides an open and transparent process for reaching a credible, defensible assessment In fact, the NRC s ability to do so was a key reason the Navy came to the NSB and BPA 8