Papers by Robert Nietubyć
arXiv (Cornell University), Oct 12, 2022
PolFEL stands for Polish Free Electron Laser, the first FEL research infrastructure in Poland. Th... more PolFEL stands for Polish Free Electron Laser, the first FEL research infrastructure in Poland. This facility is under development, and it will operate in three wavelength ranges: IR, THz and VUV, using different types of undulators. Machine will be driven by 200 MeV linear superconducting accelerator, which will operate in both, pulsed wave (PW) and continous wave (CW) modes. This paper will describe the concept, current status and the first results of the LLRF systems development.
Pd-C film growN ON SiO<inf>2</inf>/Si and Si substrates
CAS 2010 Proceedings (International Semiconductor Conference), 2010
In this paper we present results of SEM, XRD and EXAFS studies of palladium-carbon nanostructural... more In this paper we present results of SEM, XRD and EXAFS studies of palladium-carbon nanostructural films prepared in two-steps method on pure and oxidized silicon substrates. Structural, topographical and morphological differences were found between films deposited on those substrates.
Physica B: Condensed Matter, 2005
The cumulant method is a model-independent technique based on the expansion of extended X-ray abs... more The cumulant method is a model-independent technique based on the expansion of extended X-ray absorption fine structure (EXAFS) amplitudes and phases as a series of cumulants of the interatomic distance distribution. Results show evidence of simple grain boundary formed as amorphous-crystal interface region around BCC Fe nanocrystals. This interface region initially growth along with the growth of the Fe nanocrystals. However, in the latter stage of nanocrystallization, additional contribution of statically disordered interface is formed in nanograin boundaries hindering the grain growth. The disordered interfacial regions can help to explain nanocrystallization phenomenon of Fe 85 Zr 7 B 6 Cu 2 alloys.
Journal of Alloys and Compounds, 1999
Nanocrystalline Fe Zr B Cu alloys were obtained from the formerly amorphous Fe Zr B Cu alloy by a... more Nanocrystalline Fe Zr B Cu alloys were obtained from the formerly amorphous Fe Zr B Cu alloy by a heat treatment at several 85 7 6 2 85 7 6 2 temperatures ranging from 4808C to 6008C. The ultrafine nanocrystalline structure of bcc-Fe grains with a grain size of 3-15 nm diameter embedded in an amorphous matrix was established using transmission electron microscopy. X-ray absorption spectra at the Fe K-edge for Fe Zr B Cu amorphous and nanocrystalline alloys and metallic Fe foil were measured using synchrotron radiation. 85 7 6 2 Fourier analysis of extended X-ray absorption fine structure (EXAFS) for alloys was performed and two models of grain boundaries in nanocrystalline Fe Zr B Cu alloys were proposed. The heat treatment of alloys at temperatures of 4808C and 5008C creates simple 85 7 6 2 boundaries between crystalline grains and amorphous matrix, while the heat treatment at higher temperatures from 5408C to 6008C can produce boundaries in the form of Fe-free interfaces with thickness of about 0.3 nm. A model of an Fe-free interface being a barrier for grain growth can explain the nanocrystallization phenomenon of Fe Zr B Cu alloys.
This work presents the results of our research concerning the synthesis of metallic Fe-Cu coating... more This work presents the results of our research concerning the synthesis of metallic Fe-Cu coatings by use of the magnetron sputtering method. The structure of the coatings synthesized during two modes of pulsed magnetron sputtering was compared . In our experiment the pulsed magnetron power supply generated a series of pulses gated at 1kHz -standard pulsed mode (SPM) and 2 Hz -low frequency pulsed mode (LFPM). The analysis of the microstructure by means of SEM and TEM show that obtained coatings are characterized by nanocrystalline structure. Additionally the optical emission spectra (OES) during the copper and iron sputtering were measured.
On the Polfel Free Electron Laser Project
... R. Brinkmann, M. Castellano, P. Castro, L. Catani, S. Choroba, Cianchi, M. Dohlus, HT Edwards... more ... R. Brinkmann, M. Castellano, P. Castro, L. Catani, S. Choroba, Cianchi, M. Dohlus, HT Edwards, B. Faatz, AA Fateev, J. Feldhaus, K. Flöttmann, A. Gamp ... J. Bisognano, CL Bohn, L. Cardman, D. Engwall, J. Fugitt, K. Jordan, D. Kehne, Z. Li, H. Liu, L. Merminga, GR Neil, D. Neuffer ...
Journal of Micro/Nanolithography, MEMS, and MOEMS, 2005
In this contribution, we report Quantum Efficiency (QE) test results with a hybrid lead/niobium s... more In this contribution, we report Quantum Efficiency (QE) test results with a hybrid lead/niobium superconducting RF (SRF) photoinjector at 2K and new Pb arc deposited cathodes at 300K. The ultimate goal of our effort is to build a Nb injector with the superconducting cathode made of lead, which, as reported in the past, demonstrated superior QE compared to other metallic superconducting elements. At first, we present the test results obtained with a 1.6-cell high purity Nb cavity with the emitting lead spot in the center of the back plate. The QE test results at room temperature and the SEM surface analysis of eight Pb cathodes, deposited recently under various conditions, are discussed in the second part of this contribution.
R activities related to preparation of the superconducting Pb photocathode layer on niobium subst... more R activities related to preparation of the superconducting Pb photocathode layer on niobium substrate are ongoing at the National Centre for Nuclear Research (NCBJ) in cooperation with DESY, HZDR, HZB, BNL and other research institutes. The activities are part of the R program at DESY for the cw-upgrade of E-XFEL and for the newly approved free electron laser facility PolFEL to be built and operated at NCBJ. The optimization results obtained for the lead deposition on niobium and smoothing of the coated layers are reported. The photocathodes samples were tested for their surface morphology, microstructure and quantum efficiency in terms of the impact on the operation of all-superconducting RF electron injector, proposed for both facilities.
Preparation for the construction of Polish Free Electron Laser (POLFEL) will begin shortly at Nat... more Preparation for the construction of Polish Free Electron Laser (POLFEL) will begin shortly at National Centre for Nuclear Research (NCBJ) in Warsaw. POLFEL is planned as a fourth-generation light source driven by a superconducting (sc) electron accelerator. The concept includes an all-superconducting injector with a thin-film lead sc photocathode, dedicated to continuous wave or long-pulse linac operation. One of the issues which emerges in connection with operation of high-gradient electron guns furnished with dismountable photocathode plugs is the dark current emitted from the cathode surface inhomogeneities. The dark current usually degrades accelerator performance. The purpose of this paper is to present preliminary investigation results of the dark current generation in the electron gun with a thin lead layer deposited on a niobium plug. Specific features of geometric configuration like rounded plug edges, a gap between the plug and the back gun wall as well as cathode surface ...
A future upgrade of the European XFEL (E-XFEL) foresees an additional CW operation mode, which wi... more A future upgrade of the European XFEL (E-XFEL) foresees an additional CW operation mode, which will increase the flexibility in the photon beam time structure [1–3]. One of the challenges of this operational mode is the need fora CW operating photo injector. We believe that using an SRF gun is the preferred approach as the beam parameters of normal conducting pulsed guns can be potentially met by SRF guns operating CW. For more than a decade DESY, incollaboration with TJNAF, NCBJ, BNL, HZB and HZDR, has performed R&D to develop an all superconducting RFgun with a lead cathode. In the frame of E-XFEL CW upgrade feasibility studies, the SRF-gun R&D program gained more attention and support. Within the next few years we would like to demonstrate the performance of the all superconducting injector required for the E-XFEL upgrade. The selected approach offers advantages w.r.t. the cleanliness of the superconducting surface, but requires a complete disassembly of a cryostat and stripping ...
SRF Gun Cavity is an ongoing accelerator R&D project at DESY, being developed since several years... more SRF Gun Cavity is an ongoing accelerator R&D project at DESY, being developed since several years. Currently several SRF gun cavity prototypes were simulated, built and tested in our Lab and elsewhere [1] – [11]. Lately the 1.6 cells niobium cavity with Pb thin film cathode was tested in a vertical cryostat with a different cathode plug configurations. Cathode plug design was improved, as well as SRF gun cavity cleaning procedures. Results of the last cavity performance tests are presented.
Installation of the Solaris synchrotron has been accomplished at the beginning of the 2015. Altho... more Installation of the Solaris synchrotron has been accomplished at the beginning of the 2015. Although the machine is a replica of the 1.5GeV ring at MAX IV in Sweden, the entire group responsible for the installation, was facing numerous problems during the entire installation period. One of the most critical issues that are responsible for the proper functionality of the machine is the survey of the machine. An appropriate alignment of the components in accordance to each other as also to the building provides a good quality of the beam so extensively desired by the beamline’s users. This paper presents the results of the alignment in the 1.5GeV storage ring, describes possible critical sectors of the ring that might influence the accuracy of the measurements and juxtapose the results with the values gained during the operational phase of the synchrotron. This comparison enables the identification of the beam losses and extension of the lifetime of the electron beam.
To verifythe processof laser-cleaning on metal cathodes we performed a combined photoemission (PE... more To verifythe processof laser-cleaning on metal cathodes we performed a combined photoemission (PE) and scanning electron microscope (SEM) study. We followed the laser-cleaning procedure on thin Lead films arc-deposited on Mo-substrates by means of photoemission in the photon energy range of 16 – 140 eV and determined the surface roughnessbeforeandafterlaser irradiationwith whitelight-interferometry. After the cleaning procedure the morphology of the samples was as well analyzed by means of SEM. The aim of the performed experiment was to find an optimal cleaning procedure for Lead cathodes within a sc rf photoelectron injector and study its influence on the electron emission from the Lead films.
The Polish synchrotron radiation facility, Solaris, is being built in Krakow. The project is stro... more The Polish synchrotron radiation facility, Solaris, is being built in Krakow. The project is strongly linked to the MAX-IV project and the 1.5 GeV storage ring. An overview will be given of activities and of the control system and will outline the similarities and differences between the two machines.
Polish free electron laser: short technical description
Superconductivity and Particle Accelerators 2018, 2019
The Polish Free Electron Laser, PolFEL was proposed more than decade ago and at that time was acc... more The Polish Free Electron Laser, PolFEL was proposed more than decade ago and at that time was accepted for the Polish Roadmap for Research Infrastructures. The facility was proposed to be built in two stages, at first, with fewer accelerating sections and lower beam energy and the second one, with more accelerating sections, delivering 600 MeV electrons to VUV undulator, generating in the Self Amplified Spontaneous Emission process coherent radiation at wavelength ranged down to 27 nm and 9 nm in the first and third harmonic mode, respectively. Over past decade new experimental methods have been proposed and developed, delivering interesting results obtained with relatively low energy coherent and non-coherent photon beams, for example with IR-UV and THz radiation. In this contribution, subsystems of an updated version of the first stage PolFEL facility will be discussed. The project has recently received funds from the Smart Growth Operational Programme, Measure 4.2: Development of modern research infrastructure of the science sector, and is currently in a preparation phase of the construction, which will begin in 2019.
Materials Science-Poland, 2015
AlN films on a Si substrate were synthesized by magnetron sputtering method. A dual magnetron sys... more AlN films on a Si substrate were synthesized by magnetron sputtering method. A dual magnetron system operating in AC mode was used in the experiment. Processes of synthesis were carried out in the atmosphere of a mixture of Ar/N
Mechanical aspects of installation of integrated magnets at Solaris synchrotron storage ring
Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2015, 2015
Solaris synchrotron storage ring which has been assembled at the beginning of the 2015, consist o... more Solaris synchrotron storage ring which has been assembled at the beginning of the 2015, consist of twelve integrated magnets blocks performing the part of double bend achromat. Both magnets as well as the whole ring as concept is a replica of Max IV 1.5 GeV ring and utilize pioneering integrated magnets approach. Solaris ring assembly forewent that of its Swedish twin. It is a successful proof of principle experiment showing the feasibility of the chosen approach. On the other hand it was an exercise which brought the knowledge on mechanical behavior of the magnets blocks and matching components, which is of unique importance for further integrated magnets implementations. Hereby we present selected issues related to the ring assembly: block stiffness verification and straightness rectification, vacuum chamber installation, alignment and mechanical stability of the assembled system.
Ablation of Organic Molecular Solids by Focused Soft X-Ray Free-Electron Laser Radiation
Springer Proceedings in Physics
The first soft X-ray free-electron laser has recently been put into operation at DESY in Hamburg.... more The first soft X-ray free-electron laser has recently been put into operation at DESY in Hamburg. Tunable soft X-ray coherent radiation can be generated at the FLASH (Free-electron LASer in Hamburg; formerly known as VUV FEL or TTF2 FEL). In the interaction experiments reported here, the laser system provided ~ 25-fs, ~ 10-μ J pulses of 32-nm radiation. We irradiated
Radiation damages to amorphous-carbon optical coatings
SPIE Proceedings, 2005
The multi-mJ, 21-nm soft-x-ray laser at the PALS facility was focused on the surface of amorphous... more The multi-mJ, 21-nm soft-x-ray laser at the PALS facility was focused on the surface of amorphous carbon (a-C) coating, developed for heavily loaded XUV/x-ray optical elements. AFM (Atomic Force Microscopy) images show 3-micrometer expansion of the irradiated material. Raman spectra, measured with an Ar+ laser microbeam in both irradiated and unirradiated areas, confirm a high degree of graphitization in the irradiated layer. In addition to this highfluence (~ 1 J/cm2), single-shot experiment, it was necessary to carry out an experiment to investigate consequences of prolonged XUV irradiation at relatively low fluence. High-order harmonic (HH) beam generated at the LUCA facility in CEA/Saclay Research Center was used as a source of short-wavelength radiation delivering high-energy photons on the surface at a low single-shot fluence but with high-average power. a-C irradiated at a low fluence, i.e., < 0.1 mJ/cm2 by many HH shots exhibits an expansion for several nanometers. Although it is less dramatic change of surface morphology than that due to single-hot x-ray-laser exposure even the observed nanometer-sized changes caused by the HH beam on a-C surface could influence reflectivity of a grazing incidence optical element. These results seem to be important for estimating damages to the surfaces of highly irradiated optical elements developed for guiding and focusing the ultraintense XUV/x-ray beams provided by new generation sources (i.e., VUV FEL and XFEL in Hamburg; LCLS in Stanford) because, up to now, only melting and vaporization, but not graphitization, have been taken into account.
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Papers by Robert Nietubyć