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NGLS Technical Overview

Comparison of NGLS X-ray pulse structure with other light source types

Today is a golden age for light sources. Storage-ring–based synchrotrons routinely provide X-ray beams exploited by thousands of scientists annually to answer fundamental questions in diverse fields, including human health, energy, and electronics and information processing. Recently, a remarkable new tool, the world’s first hard X-ray laser, began operation: The Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory has exceeded performance expectations and opened the door to the X-ray laser era. Early experiments from LCLS are illustrating the promise of X-ray lasers and establishing a strong user community for them; yet a next-generation X-ray laser already is clearly needed to realize the full potential of this new tool.

NGLS Capabilities

  • High pulse repetition rates (100 kHz or higher at each experimental end station, 1 MHz at specific end stations).
  • Very high average flux and brightness, several orders of magnitude greater than third-generation rings and first-generation FELs, with peak powers of up to gigawatt and average powers of greater than 100 Watts in some beamlines.
  • Pulse durations ranging from femtosecond to hundreds of femtoseconds, and with special beamlines sub-femtosecond pulses at reduced power.
  • High temporal coherence of FEL output pulses (close to the Fourier transform limit).
  • High transverse coherence (approaching diffraction limits).
  • Control of time duration and bandwidth of the pulses.
  • Excellent spectral resolving power.
  • Synchronization and instrumentation to enable timing of the FEL pulses to a seed laser or to other infrared (IR) or THz sources with jitter on the order of 10 fs or less.
  • FEL output photon energy (including harmonics) extending into the hard X-ray region, from ~50 eV to ~6 keV.
  • Precision, two-color X-ray pump–X-ray probe experiments.
  • Precision pump-probe experiments with combined probes in the soft X-ray or extreme ultraviolet (EUV) range and pumps in the UV, optical, IR, THz, or other bands.
  • Polarization control.
  • Multiple independent beamlines supporting a large user community.

As a transformative tool for science, the planned Next Generation Light Source will comprise an array of X-ray lasers providing temporally and spatially coherent pulses with unprecedented average brightness extending beyond 1 keV. Individual lasers and beamlines will be optimized for specific applications requiring, for example, high repetition rates, time resolution to the femtosecond (fs) regime, high spectral resolution, tunability, and polarization control. This powerful combination of capabilities will enable cinematic imaging of dynamics, determination of the structure of heterogeneous systems, and development of novel nonlinear X ray spectroscopies. These unique resources will lead to a new understanding of how electronic and nuclear motions in molecules and solids are coupled and how functional systems perform and evolve in situ.

Based on a modern superconducting linear accelerator and leveraging the latest laser-seeding technologies, the proposed NGLS will provide the high repetition rate and high average coherent power needed to go beyond the initial stage of X-ray lasers. These capabilities will enable scientists to answer fundamental questions in a wide range of disciplines.

Comparison of NGLS average brightness with other light source types