1,721,046 research outputs found
Characterization of the ENEA extreme ultraviolet radiation discharge produced plasma source, by using diamond detectors developed at the University of Rome “Tor Vergata”
No full textAfter a brief introduction, including a summing up of the main characteristics of the Extreme Ultraviolet (EUV) radiation, we describe the ENEA Discharge Produced Plasma (DPP) EUV source. The DPP emits 100-ns duration EUV pulses, in the λ = 10–18 nm wavelength spectral range. The in-band energy per pulse is about 30 mJ/sr at 10 Hz repetition rate. In addition to the already performed characterizations, we recently exploited high purity monocrystalline diamond
detectors developed at the Department of Industrial Engineering of the University of Rome “Tor Vergata”. The configuration of the electrodes of the used devices was
the interdigitated one, particularly suitable for fast measurements. Thanks to the rapid temporal response of these detectors, the fast peaks of EUV emission (7–8 ns FWHM), superimposed on the main pulses, have been characterized much better than when using silicon PIN diodes. These rapid emission peaks occur at the maximum heating and radial compression of the plasma column. Finally, by using the
DPP source, a useful characterization and calibration of the diamond detectors has been obtained in the λ = 10–18 nm range, by comparison with a reference absolute PIN diode
La sorgente "DPP" di radiazione nell'estremo ultravioletto a scarica elettrica in gas rarefatto. Principi fisici, caratterizzazione ed ottimizzazione
Full text linkIn questo rapporto vengono descritti i lavori di installazione, miglioramento e caratterizzazione della sorgente di radiazione nell'estremo ultravioletto a scarica elettrica dell'ENEA (UTAPRAD-SOR). La sorgente, inizialmente progettata e realizzata in collaborazione tra l'ENEA ed il Dipartimento di Fisica dell'Università dell'Aquila, è stata trasferita all'ENEA (Frascati) nell'aprile 2010, priva, però, di molti componenti fondamentali. Per mettere in funzione la sorgente, non disponendo di fondi dedicati, è stato necessario riutilizzare, modificandoli opportunamente, materiali e dispositivi già presenti all'ENEA. Inoltre, per migliorare il funzionamento e le caratteristiche della sorgente, si è provveduto a modificarne radicalmente varie parti, affrontando diverse problematiche fisiche nell'analisi dei principi di funzionamento della sorgente. Attualmente la sorgente è operativa e le sue caratteristiche la rendono idonea per varie applicazioni. Con l'intento di fornire una prima base ad un eventuale futuro studente, in questo rapporto i principi fisici di funzionamento della sorgente e le problematiche affrontate sono stati trattati anche da un punto di vista didattico.In this report we describe the installation, upgrade and characterisation of the ENEA (UTAPRAD-SOR) extremeultraviolet electric discharge source. In April 2010 the source, initially developed in the framework of a collaboration between ENEA and the Physics Department of the University of L'Aquila, has been transferred to ENEA (Frascati), but without many important components. To make the source working, having no dedicated funds, it was necessary to reutilise and properly modify materials and devices already present in ENEA. In order to improve some source features, several critical components of the source have been totally redesigned, analyzing the source working principles and solving various physical problems. Now the source is operating and, due to its characteristics, it is suitable for many applications. With the aim of giving a possible future student a starting point, in this report the source working principles and the scientific problems that we ran into, have been also didactically treated
Surface-enhanced Raman spectroscopy characterisation of functionalised multi-walled carbon nanotubes
No full textMulti-walled nanotube (MWNT) functionalisation was investigated by surface-enhanced Raman spectroscopy (SERS). The MWNTs were deposited as dilute dispersions on SERS-active substrates. We used nano-structured gold surfaces with various morphologies for our measurements. The surface enhancement effect was used to amplify the Raman signal from functional molecules bound to the nanotube walls. The recorded spectral features allowed for discrimination between the differently functionalised MWNTs. Although the present study is limited to a few examples, our measurements indicate the higher specificity obtained by the SERS approach and its possible use for a systematic study of functionalisation effects on MWNT structures. © the Owner Societies 2015
Design of a plasma discharge circuit for particle wakefield acceleration
No full textPlasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV m -1), enabling acceleration of electrons to GeV energy in few centimetres. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators; radiofrequency-based accelerators, in fact, are limited in the accelerating field (10-100 MV m-1) requiring therefore kilometric distances to reach the GeV energies, but can provide very bright electron bunches. Combining high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC-LAB [1,2]. In particular, here we focus on the ionization process; we show a simplified model to study the evolution of plasma induced by discharge, very useful to design the discharge circuit able to fully ionize the gas and bring the plasma at the needed temperature and density. © 2013 Elsevier B.V
Monitoring of Cleaning Treatments for Paper Heritage with Raman Spectroscopy Mapping
Full text linkIn the field of book heritage, it is important to develop cleaning/disinfecting treatments that can slow down the degradation of paper to prevent evident and irreversible damage. The objectives of the cleaning treatments are to remove external contaminants and oxidation and decomposition products of the paper, but these processes must not modify the unique characteristics of the book heritage resulting in irreversible changes in the structure of the paper. Recently, several innovative cleaning treatments were developed with the aim of being minimally invasive; however, to assess the effect of these treatments on paper, it is necessary to use a diagnostic non-destructive, rapid, and affordable process. In previous work, we used surface scanning Raman spectroscopy to develop a diagnostic protocol able to follow the aging processes of the paper, discriminating between hydrolysis and oxidation. In this paper, we applied this protocol to study the action of different types of treatments (hydrogel and EUV irradiation), evaluating both their effectiveness and impact on paper parameters. The results reported here demonstrate that the developed in operando diagnostic procedure can follow the changes in the paper structure comparing them to the variability due to the intrinsic inhomogeneity of paper, without sample contact in a rapid and effective way
ENEA EUV discharge produced plasma source: Diagnostics, characterization and applications
No full textExtreme Ultraviolet (EUV) radiation (photon energy hn = 20-284eV, wavelength λ ≃ 4:4-62nm) can be used to efficiently modify the structure of photonic materials, photoresists etc. In fact, the EUV short wavelength, its short penetration length in matter (typically few tens of nm) and the availability of high-reflectivity (≥ 70% at λ = 13-15nm) normal-incidence multilayer mirrors allow high-spatial-resolution patterning on the aforementioned materials. This is leading to the development of the next generation lithography for micro-electronics. Consequently, EUV sources are a main object of study and they are largely exploited for metrology and tests on mirrors, innovative materials etc. Excluding large facilities like synchrotron machines, plasma sources are needed to efficiently generate EUV radiation. An EUV discharge produced plasma source is operating at the ENEA Frascati Research Centre. The source characterization by means of various diagnostic tools will be reported after a brief description of its principle of operation. Finally, some source applications involving the treatment of both photonic materials and innovative photoresists will be illustrated. © Copyright 2015 ITER Organization
Linear undulator brightness: Inclusion of sextupolar magnetic-field contributions and of higher-order energy corrections
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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