Browsing by Author "Pietag, F."
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- ItemGratings for synchrotron and FEL beamlines: a project for the manufacture of ultra-precise gratings at Helmholtz Zentrum Berlin(Chester : IUCr, 2018) Siewert, F.; Löchel, B.; Buchheim, J.; Eggenstein, F.; Firsov, A.; Gwalt, G.; Kutz, O.; Lemke, St.; Nelles, B.; Rudolph, I.; Schäfers, F.; Seliger, T.; Senf, F.; Sokolov, A.; Waberski, Ch.; Wolf, J.; Zeschke, T.; Zizak, I.; Follath, R.; Arnold, T.; Frost, F.; Pietag, F.; Erko, A.Blazed gratings are of dedicated interest for the monochromatization of synchrotron radiation when a high photon flux is required, such as, for example, in resonant inelastic X-ray scattering experiments or when the use of laminar gratings is excluded due to too high flux densities and expected damage, for example at free-electron laser beamlines. Their availability became a bottleneck since the decommissioning of the grating manufacture facility at Carl Zeiss in Oberkochen. To resolve this situation a new technological laboratory was established at the Helmholtz Zentrum Berlin, including instrumentation from Carl Zeiss. Besides the upgraded ZEISS equipment, an advanced grating production line has been developed, including a new ultra-precise ruling machine, ion etching technology as well as laser interference lithography. While the old ZEISS ruling machine GTM-6 allows ruling for a grating length up to 170 mm, the new GTM-24 will have the capacity for 600 mm (24 inch) gratings with groove densities between 50 lines mm−1 and 1200 lines mm−1. A new ion etching machine with a scanning radiofrequency excited ion beam (HF) source allows gratings to be etched into substrates of up to 500 mm length. For a final at-wavelength characterization, a new reflectometer at a new Optics beamline at the BESSY-II storage ring is under operation. This paper reports on the status of the grating fabrication, the measured quality of fabricated items by ex situ and in situ metrology, and future development goals.
- ItemHuman health risk evaluation of a microwave-driven atmospheric plasma jet as medical device(Amsterdam [u.a.] : Elsevier, 2017) Lehmann, A.; Pietag, F.; Arnold, T.Purpose: The aim of this study was the characterisation of a microwave-driven atmospheric plasma jet (APJ) dedicated for medical applications. The scientific focus includes harmless sterilization of surfaces and therapeutic treatments in dentistry. Methodes: The plasma was investigated with respect to potential health risks for human beings, which could occur especially by the gas temperature, heat flow, patient leakage current, UV emission and ozone emission from the plasma jet, according to DIN SPEC 91315:2014-06 (General requirements for plasma sources in medicine) [1]. Results: The results of the experiments indicate a high potential of the plasma jet to be used as a medical device exhibiting low gas temperatures up to 34 °C. The calculated leakage currents are mostly below the 10 μA threshold. The limiting UV exposure duration for the APJ with a calculated maximum effective irradiance of 2.6 μW/cm2 is around 19 min, based on the exposure limits of the international commission on non-ionizing radiation protection guidelines (ICNIRP) [2]. A significant ozone concentration was observed mainly in the axial effluent gas flow. Ozone concentration strongly decreases with increasing distance from the plasma source exit nozzle. Conclusion: The investigated APJ exhibits physical properties that might not constitute health risks to humans, e.g. during treatment in dentistry. Thus, the APJ shows a high potential for application as a device in dental therapy.