Stable operation of a self-amplified spontaneous-emission free-electron laser in the extremely ultraviolet region

Abstract

We achieved stable operation of a free-electron laser (FEL) based on the self-amplified spontaneousemission (SASE) scheme at the SPring-8 Compact SASE Source (SCSS) test accelerator in the extremely ultraviolet region. Saturation of the SASE FEL power has been achieved at wavelengths ranging from 50 to 60 nm. The pulse energy has reached $30 J at 60 nm. The observed fluctuation of the pulse energy is about 10% (standard deviation) for several hours, which agrees with the expectation from the SASE theory showing the stable operation of the accelerator. The SASE FEL has been routinely operated to provide photon beams for user experiments over a period of a few weeks. Analysis on the experimental data gave the normalized-slice emittance at the lasing part is around 0:7 mm mrad. This result indicates that the normalized-slice emittance of the initial electron beam, 0:6 mm mrad in a 90% core part, is kept almost unchanged after the bunch compression process with a compression factor of approximately 300. The success of the SCSS test accelerator strongly encourages the realization of a compact XFEL source.

Ablation by short optical and x-ray laser pulses

“…It can provide laser pulses in the extreme-ultraviolet (EUV) region (51-62 nm). [5][6][7] In our experiments SCSS worked at wavelengths about 61.5 nm. We have used a single shot mode, which allows to measure the laser energy in each shot.…”

“…Equations (1)(2)(3) are solved together with hydrodynamical equations (4)(5)(6). Lagrangian variable x 0 is linked to moving substance.…”

“…The duration of the pulse was about 300 fs. 6 The Kirkpatrick-Baez microscope, based on ellipsoidal and cylindrical mirrors coated by SiC multilayers was used to focus EUV beam at the distance about 100 cm from the mirror output. The transmission of the microscope is ∼ 70%.…”

TOF-OFF: A method for determining focal positions in tightly focused free-electron laser experiments by measurement of ejected ions

“…Compact SASE Source) [3] and Italy (FERMI@Elletra, Free Electron Laser for Multidisciplinary Investigations) [4], and several similar light sources are being planned across the globe. These brilliant sources use X-rays to study physical processes relevant to a range of disciplines, from structural biology to plasma physics.…”

High-Gain Harmonic-Generation Free-Electron Laser Seeded by Harmonics Generated in Gas

“…In the self-amplified spontaneous emission (SASE) configuration [8][9][10][11], the e.m. radiation is the spontaneous emission of the electrons. SASE FELs can deliver very short wavelengths [6,7,12,13], but suffer a limited temporal coherence [11,14] due to the intrinsic fluctuations of the initial shot noise. In the seeded amplifier configuration [15,16], the optical radiation is an external coherent source, which enables to reach a higher degree of temporal coherence within a shorter distance.…”