We present the first lasing results of SwissFEL, a hard X-ray free-electron laser (FEL) that recently came into operation at the Paul Scherrer Institute in Switzerland. SwissFEL is a very stable, compact and cost-effective X-ray FEL facility driven by a low-energy and ultra-low-emittance electron beam travelling through short-period undulators. It delivers stable hard X-ray FEL radiation at 1-Å wavelength with pulse energies of more than 500 μJ, pulse durations of ~30 fs (root mean square) and spectral bandwidth below the per-mil level. Using special configurations, we have produced pulses shorter than 1 fs and, in a different set-up, broadband radiation with an unprecedented bandwidth of ~2%. The extremely small emittance demonstrated at SwissFEL paves the way for even more compact and affordable hard X-ray FELs, potentially boosting the number of facilities worldwide and thereby expanding the population of the scientific community that has access to X-ray FEL radiation.

我们展示了SwissFEL的第一个激光结果，这是一种最近在瑞士Paul Scherrer研究所投入使用的硬X射线自由电子激光器（FEL）。SwissFEL是一种非常稳定，紧凑且具有成本效益的X射线FEL装置，由低能量和超低发射率电子束通过短周期波荡器驱动。它以1-Å波长提供稳定的硬X射线FEL辐射，脉冲能量超过500μJ，脉冲持续时间约30 fs（均方根），光谱带宽低于密尔级。使用特殊的配置，我们产生的脉冲短于1 fs，在不同的设置下，宽带辐射的带宽达到前所未有的2％。在SwissFEL上展示的极小的发射率为更紧凑，价格更便宜的硬X射线FEL铺平了道路，