NanoESCAContactResearchBeamline DescriptionSpecificationsPhD positions
NanoESCA beamline description
Beamline flux
Refocussing optics
Insertion device
The NanoESCA beamline shares the insertion device with the Nanospectroscopy beamline. Based on the Sasaki Apple II scheme, it consists of two identical undulator sections (Elettra insertion devices 1.1 and 1.2) and a phase modulation electromagnet arranged in an optical klystron configuration. This enables the two undulators to be properly phased, thus effectively doubling the undulator length and the useful flux. The insertion device is able to provide elliptically polarized light (circular left and right as well as linear horizontal and vertical as special cases) in a spectral range extending from 50 eV to 1000 eV, with high brilliance (using the first, third and fifth undulator harmonic). We emphasis the undulator capability of helicity inversion, which allows performing XMCD (X-Ray Magnetic Circular Dichroism) measurements. The optimum phase for measurements requiring circular polarisation can be found here.
Beamline Layout
The light source is the middle-point (4) between the undulator two sections (1) and (2) with phase modulator electromagnet (3).At 10 m from the source middle position, the pinhole (5) sets the beamline angular acceptance and stops unwanted radiation from the undulator.The toroidal mirror (6) demagnifies the source by a factor of 8 in the horizontal plane and 5.3 in the vertical. The entrance slits are located at the horizontal (7) and vertical (8) foci of the toroidal mirror. The slit (7) becomes the virtual source for all of the following mirrors in the horizontal plane. The light is then dispersed by the monochromator (9),which also determines a further vertical demagnification by a factor 1.7. After the exit-slit (10), a retractable plane mirror (11) allows switching operation between the two branches of the beamline. The refocusing mirrors are two bendable elliptical cylinder mirrors arranged in a Kirkpatrick-Baez geometry. They are located in dedicated vacuum chambers (12). The SPELEEM microscope (13). The NanoESCA photoemmission microscope (14). On the beamline first branch, the demagnification introduced by these elements is 11.5 in the horizontal direction and 5 in the vertical direction. For the NanoESCA (second branch), the demagnification factors are 13.9 and 7.6, for the horizontal and the vertical direction respectively.
Last Updated on Tuesday, 10 January 2012 17:35