198 research outputs found
First experiments with the negative ion source NIO1
Neutral Beam Injectors (NBIs), which need to be strongly optimized in the perspective of DEMO reactor, request a thorough understanding of the negative ion source used and of the multi-beamlet optics. A relatively compact radio frequency (rf) ion source, named NIO1 (Negative Ion Optimization 1), with 9 beam apertures for a total H- current of 130 mA, 60 kV acceleration voltage, was installed at Consorzio RFX, including a high voltage deck and an X-ray shield, to provide a test bench for source optimizations for activities in support to the ITER NBI test facility. NIO1 status and plasma experiments both with air and with hydrogen as filling gas are described. Transition from a weak plasma to an inductively coupled plasma is clearly evident for the former gas and may be triggered by rising the rf power (over 0.5 kW) at low pressure (equal or below 2 Pa). Transition in hydrogen plasma requires more rf power (over 1.5 kW)
Appunti di Liberty milanese
Rapido excursus di inquadramento sull'arte liberty in Italia e a Milano, con alcune realizzazioni architettoniche e scultoree-decorative dei maggiori artisti del tempo e un focus su Giuseppe Sommaruga a Palazzo Castiglioni
Modeling and design of a BES diagnostic for the negative ion source NIO1
Consorzio RFX and INFN-LNL are building a flexible small ion source (NIO1)
capable of producing about 130 mA of H- ions accelerated at 60 KeV. Aim of the
experiment is to test and develop the instrumentation for SPIDER and MITICA,
the prototypes respectively of the negative ion sources and of the whole
neutral beam injectors which will operate in the ITER experiment. As SPIDER and
MITICA, NIO1 will be monitored with Beam Emission Spectroscopy (BES), a
non-invasive diagnostic based on the analysis of the spectrum of the
emission produced by the interaction of the energetic ions with the background
gas. Aim of BES is to monitor direction, divergence and uniformity of the ion
beam. The precision of these measurements depends on a number of factors
related to the physics of production and acceleration of the negative ions, to
the geometry of the beam and to the collection optics. These elements were
considered in a set of codes developed to identify the configuration of the
diagnostic which minimizes the measurement errors. The model was already used
to design the BES diagnostic for SPIDER and MITICA. The paper presents the
model and describes its application to design the BES diagnostic in NIO1.Comment: 3 pages, 3 figures. Contributed paper for the ICIS 2013 conference.
Accepted manuscrip
First Beam Characterization by Means of Emission Spectroscopy in the NIO1 Experiment
The NIO1 experiment hosts a flexible RF H- ion source, developed by INFN-LNL
and Consorzio RFX to improve the present concepts for the production and
acceleration of negative ions. The source is also used to benchmark the
instrumentation dedicated to the ITER neutral beam test facility. Many
diagnostics are installed in NIO1 to characterize the source and the extracted
negative ion beam. Among them, Beam Emission Spectroscopy (BES) has been used
in NIO1 to measure the divergence and the uniformity of the beam, together with
the fraction of beam ions which was neutralized inside the acceleration system.
The diagnostic method is based on the analysis of the Doppler shifted
photons emitted by the fast beam particles and collected along a
line of sight. The article presents the experimental setup and the analysis
algorithms of the BES diagnostic, together with a discussion of the first
measurements and of their correlation with the operational parameters.Comment: 3 pages, 2 figures. Contributed paper for the ICIS 2017 conference.
Accepted manuscript of a published pape
First hydrogen operation of NIO1: characterization of the source plasma by means of an optical emission spectroscopy diagnostic
NIO1 is a compact and flexible radiofrequency H- ion source, developed by
Consorzio RFX and INFN-LNL. Aim of the experimentation on NIO1 is the
optimization of both the production of negative ions and their extraction and
beam optics. In the initial phase of its commissioning, NIO1 was operated with
nitrogen, but now the source is regularly operated also with hydrogen. To
evaluate the source performances an optical emission spectroscopy diagnostic
was installed. The system includes a low resolution spectrometer in the
spectral range of 300-850 nm and a high resolution (50 pm) one, to study
respectively the atomic and the molecular emissions in the visible range. The
spectroscopic data have been interpreted also by means of a
collisional-radiative model developed at IPP Garching. Besides the diagnostic
hardware and the data analysis methods, the paper presents the first plasma
measurements across a transition to the full H mode, in a hydrogen discharge.
The characteristic signatures of this transition in the plasma parameters are
described, in particular the sudden increase of the light emitted from the
plasma above a certain power threshold.Comment: 3 pages, 2 figures. Contributed paper for the ICIS 2015 conference.
Accepted manuscrip
Excitation of the l=2 diocotron mode with a resistive load
The resistive wall instability of the l=2 diocotron mode in a pure electron plasma has been investigated with a systematic variation of the parameters of the external impedance connected to a pair of sectored electrodes. The measured growth rate is well described by a linear perturbation theory of the two-dimensional drift-Poisson system
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