Search results for "Mirrors"
showing 8 items of 18 documents
Background Rejection of Charged Particles in the Simbol-X Telescope: Preliminary Study of Protons Scattering
2009
X-ray telescopes equipped with focusing optics in high eccentric orbit, as e.g. Newton-XMM and Chandra, showed a degradation of the detector performance and an important increase of the noise due to soft protons with energy between a few tens of keV and a few MeV, that are focused on the detector through the mirror module. It should be noted that the focusing of the protons by Wolter optics was an unexpected phenomenon. In Simbol-X a magnetic diverter will be implemented to deflect protons, in order to reduce the flux of charged particles impinging upon the focal plane. Obviously the design of the diverter should take into consideration the protons distribution at the exit of the mirror mod…
A multichannel piezo driver for active mirrors in X-ray telescopes
2016
X-ray astronomy is gaining importance for studying X-ray space sources such as single and binary stars, neutron stars, supernovae and black holes. Due to atmospheric absorption, X-ray telescopes must operate in space on satellites. Among the causes limiting the resolution of modern telescopes are distortions in mirrors shape. An innovative approach for X-ray mirrors aims at correcting the shape errors by means of piezo-ceramic actuators glued to the back of the mirrors, thus creating an “active mirror”. In order to test the viability of shape correction, we fabricated [1] a prototype of a thin glass active mirror, sized 20 cm x 20 cm with a 400 um thickness (Fig. 1). The mirror can allocate…
Gli specchi argentati della Collezione Storica degli Strumenti di Fisica dell’Università di Palermo
2021
Nell'articolo presenteremo tre strumenti scientifici di particolare interesse storico-didattico appartenenti alla Collezione Storica degli Strumenti di Fisica dell'Università di Palermo: uno specchio convesso risalente molto probabilmente all'inizio del XIX secolo e una coppia di specchi ustori risalenti molto probabilmente alla metà del XIX secolo. Dopo un'introduzione sullo sviluppo storico degli specchi e il loro principio di funzionamento, descriveremo le caratteristiche fisiche degli strumenti della collezione e gli interventi effettuati. In the paper we will describe three instruments of particular historical and didactic interest belonging to the Historical Collection of Physics Inst…
Astronomical soft x-ray mirrors reflectivity enhancement by multilayer coatings with carbon overcoating
2004
A number of X-ray astronomical missions of near future will make use of hard X-ray optics with broad-band multilayer coatings. However multilayer mirrors can be also useful to enhance the effective area of a given X-ray telescope in the "classical" low energy X-ray band (0.1 – 10 keV), the window where X-ray spectroscopy provides very useful plasma diagnostics) with a consistent gain with respect to usual single-layer reflectors. Multilayers for soft X-rays are based on stacks with constant d-spacing (in order to minimize the loss due to the photoelectric effect). A further gain in reflectivity (however only restricted to the energy range between 0.5 and 4 keV) can be achieved by using a lo…
Combination of simple mirrors – childish game or useful tool?
2015
International audience; The Scottish inventor of the kaleidoscope, Sir David Brewster (1781-1868), examined references to previous combinations of mirrors in his defense of his own invention, The Kaleidoscope, Its History, Theory and Construction (1858). Sir David Brewster who was eager to prove that his invention, dating back to 1816, was genuinely innovative, dismissed the use of what he called “combinations of plane mirrors” as productive of “poor effect”. His examination of the mirror devices described in the works of Gianbattista della Porta (1535-1615) Athanasius Kircher (1601-1680) and Richard Bradley (1688-1732), led him to the conclusion that they could hardly have been the result …
Experimental evidence on microwave induced electron losses from ECRIS plasma
2018
The balance between warm and hot (>1 keV) electron density and their losses from the magnetic confinement system of an Electron Cyclotron Resonance Ion Source (ECRIS) plasma is considered to be one of the main factors determining the rate of the high charge state ion production. One of the key loss channels for heated electrons is thought to be induced by the injected microwaves. While this loss mechanism, referred to as rf-induced pitch angle scattering, has been studied theoretically and with computational tools, direct experimental evidence of its significance in minimum-B ECRIS plasmas remains limited. In this work, experimental evidence of microwave induced electron losses in the axial…
Influence of axial mirror ratios on the kinetic instability threshold in electron cyclotron resonance ion source plasma
2022
International audience; Electron Cyclotron Resonance (ECR) ion source plasmas are prone to kinetic instabilities. The onset of the instabilities manifests as emission of microwaves, bursts of electrons expelled from the plasma volume, and the collapse of the extracted highly charged ion (HCI) currents. Consequently, the instabilities limit the HCI performance of ECR ion sources by limiting the parameter space available for ion source optimization. Previous studies have shown that the transition from stable to unstable plasma regime is strongly influenced by the magnetic field structure, especially the minimum field value inside the magnetic trap (Bmin). This work focuses to study the role o…
Turystyczny przewodnik po Piekle Mikołaja Reja, czyli o międzyplanetarnych podróżach duszy ludzkiej
2020
The article deals with the complex issue of presenting the underworld in the Reja's Wizerunk. The author draws attention to the presence in the output of the old Polish poet of many visionary elements borrowed from the most varied traditions and religious systems. The popular pattern of searching for spiritual perfection, fixed in the archetype of the topographic movement of the hero (Latin: Homo viator) turns out to be particularly visible. It turns out that at the very foundations of this imaginative pattern there is an ancient doctrine or interplanetary wandering of the soul. Most of the work was focused on the description of XI songs of Reja’s WizerunV, where a description of hell appea…