Generation of Soft X-Ray/VUV Photons with a Hybrid/Bias Micropole Undulator on the LLNL Linac.

The recently introduced class of micropole undulators, i.e., undulators with submilli-meter periods, promises a wide variety of useful applications in x-ray science and technology. One of the most important of these could turn out to be the efficient generation of highly coherent soft x rays on economical low-energy storage rings or linacs. Over the last year and a half, an intensive experimental effort has been in progress at the Lawrence Livermore National Laboratory (LLNL) to characterize the radiation emitted on a linac by a novel hybrid/bias micropole undulator fabricated at the Stanford Synchrotron Radiation Laboratory. In this initial report, the properties of this new 706-µm-period insertion device and its generation of 66-eV soft x rays on the LLNL linac are described. Although in the present experiment power levels of a fraction of a picowatt at linac currents of several tens of picoamperes were generated, this was in agreement with theoretical predictions. Operation of our prototype device on a higher energy machine at currents of several milliamperes could consequently be expected to produce milliwatt levels of soft x-ray output, making it an x-ray source potentially competitive with bending magnets on high-energy storage rings.

Nanosecond gating of an optical multichannel analyzer.

An optical gating pulse of 30 ns width combined with an electronic gating pulse of 50 ns width has been found to give a near perfect performance of a gated silicon intensified vidicon detector. The magnification as well as the focusing properties are found to be close to the real-time behavior and the small changes that do occur in the gated mode can be corrected for in the data analysis.

Diffraction grating transmission efficiencies for XUV and soft x rays.

Efficiencies for diffraction of 45-275-eV x rays into orders by interferometrically formed, electrodeposited, gold transmission gratings have been measured on the 4 degrees beam line at the Stanford Synchrotron Radiation Project (SSRP). Anomalous dispersion affects the observed efficiency since the gold is partially transmitting to x rays. Model calculations which include anomalous dispersion are in good agreement with observations. With a suitable choice of material and thickness, a grating can be optimized for a given wavelength range by reducing the zero order transmission and enhancing the higher orders. Even orders are suppressed for a grating with equal slit and wire sizes.