Session L18: Advanced Techniques in Acceleration and Coherent Radiation

Recent Advances in X-Ray Free Electron Lasers

X-ray free electron lasers(FELs) are undergoing an exciting development. They will soon become a reality with the commissioning of the LCLS in early next year, soon followed by Spring 8 X-FEL and the European XFEL at Hamburg. Intense, coherent pulses of x-rays from these machines will permit exploration of the atomic world with spatial and temporal precisions hitherto not feasible. After these first generation x-ray FELs based on self-amplified spontaneous emission (SASE) in a single pass high-gain system, the next generation devices for higher performance and/or smaller and lower cost are under various stages of development. In the soft x-ray region, seeded FELs with high harmonic generated (HHG) laser input will produce coherent output in a shorter system. Drastic improvement in hard x-ray region is possible with new types of electron injectors producing electron beams with an order of magnitude smaller emittance. Hard x-ray FELs can be built with an order of magnitude smaller electron energy and thus with a significant savings in the cost. The Spring-8 FEL is a first step in this direction. Novel types of FELs are possible; ultra-short SASE providing sub-fs time-resolution and x-ray FEL oscillator (XFELO) providing ultra-narrow spectral resolution. The XFELO employs optical cavity formed by Bragg reflectors, delivering temporally and spatially coherent hard x-rays, with meV spectral resolution. Its peak spectral brightness is similar to but the average spectral brightness is about five orders of magnitudes higher than LCLS.   

Novel Techniques for the Generation of Ultrashort Attosecond Pulses of Coherent Radiation

Revealing the laws of Nature often require developing unique experimental tools. In this talk I will discuss new tools that will enable probing of matter with attosecond time resolution and Angstrom spatial resolution. Their emergence is largely due to the spectacular progress in development of x-ray free electron lasers and similar progress in generation of the ultra-short light pulses in optics.   

Emerging Long-Wavelength Coherent Light Sources---from the infrared to soft X-rays

The theory and techniques of accelerator-based coherent light sources will be discussed. Application of these ideas to the design of user facilities from the IR to soft X-rays will be presented, including world-wide initiatives for next generation light source R{\&}D and construction at these longer wavelengths.