Influence of the magnetic filter field topology on the beam divergence at the ELISE test facility

The ELISE test facility hosts a RF negative ion source, equipped with an extraction system which should deliver half the current foreseen for the ITER Neutral Beam Injector, keeping the ratio of co-extracted electrons to ions below 1. An important tool for the suppression of the co-extracted electrons is the magnetic filter field, produced by a current flowing in the plasma grid, the first grid of the 3 stage extraction system. To boost the source performances new concepts for the production of the magnetic filter field have been tested, combining the existing system with permanent magnets attached on the source walls. The topologies of these new magnetic configurations influence the beam particles trajectories in the extraction region, with consequences for the overall beam optics. These effects will be characterized in this article by studying the angular distribution of the beam particles, as measured by the Beam Emission Spectroscopy (BES) diagnostic. The behavior of the beam will be studied also through the measurements of the currents flowing on the grounded grid (the third grid) and on the grid holder box surrounding its exit. The main finding is that the broader component of the beam increases when the magnetic field is strengthened by permanent magnets, i.e. in the cases in which most of the co-extracted electrons are suppressed.Comment: 7 pages, 4 figures. Contributed paper for the NIBS 2016 conference. Accepted manuscrip

Modeling and simulation of a beam emission spectroscopy diagnostic for the ITER prototype neutral beam injector

A test facility for the development of the Neutral Beam Injection system for ITER is under construction at Consorzio RFX. It will host two experiments: SPIDER, a 100 keV H-/D- ion RF source, and MITICA, a prototype of the full performance ITER injector (1 MV, 17 MW beam). A set of diagnostics will monitor the operation and allow to optimize the performance of the two prototypes. In particular, Beam Emission Spectroscopy will measure the uniformity and the divergence of the fast particles beam exiting the ion source and travelling through the beam line components. This type of measurement is based on the collection of the H{\alpha}/D{\alpha} emission resulting from the interaction of the energetic particles with the background gas. A numerical model has been developed to simulate the spectrum of the collected emissions in order to design this diagnostic and to study its performance. The paper describes the model at the base of the simulations and presents the modeled $H_\alpha$ spectra in the case of MITICA experiment.Comment: 4 pages, 5 figures. Contributed paper for the HTPD 2014 conference. Accepted manuscrip

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 $H_\alpha$ 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 $H_\alpha$ 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

Beam characterization by means of emission spectroscopy in the ELISE test facility

The ELISE test facility at IPP Garching hosts a RF H-/D- ion source and an acceleration system. Its target is to demonstrate the performance foreseen for the ITER NBI system in terms of extracted current density (H/D), fraction of co-extracted electrons and pulse duration. The size of the ELISE extraction area is half that foreseen for the ITER NBI. This paper presents a detailed study of the ELISE beam divergence and uniformity. In particular, it was possible to describe the beam as the sum of two components at very different divergence: about 2{\deg} vs. 5{\deg}{\div}7{\deg}. As test cases, the beam properties have been measured as function of two source parameters. The first one is the current flowing through the grid facing the plasma, the Plasma Grid, in order to generate the magnetic filter field. The second one is the bias current flowing between the Plasma Grid and the source walls. Both the filter field and the bias current influence the fraction of co-extracted electrons, but also the properties of the plasma just in front of the extraction system and the beam properties. The divergence and the uniformity of the beam have been measured by a Beam Emission Spectroscopy (BES) diagnostic; the detailed analysis of the raw spectra collected by BES led to describing the beam with two components of different divergence. This concept has been supported by the information given by thermal imaging of the diagnostic calorimeter. Further support to the proposed beam model has been found in the behavior of the currents flowing in the acceleration system and beamline components; these currents are given by the most divergent (charged) particles of the beam.Comment: 15 pages, 8 figures. Accepted manuscript (embargo expired

Electron Density and Temperature in NIO1 RF Source Operated in Oxygen and Argon

The NIO1 experiment, built and operated at Consorzio RFX, hosts an RF negative ion source, from which it is possible to produce a beam of maximum 130 mA in H- ions, accelerated up to 60 kV. For the preliminary tests of the extraction system the source has been operated in oxygen, whose high electronegativity allows to reach useful levels of extracted beam current. The efficiency of negative ions extraction is strongly influenced by the electron density and temperature close to the Plasma Grid, i.e. the grid of the acceleration system which faces the source. To support the tests, these parameters have been measured by means of the Optical Emission Spectroscopy diagnostic. This technique has involved the use of an oxygen-argon mixture to produce the plasma in the source. The intensities of specific Ar I and Ar II lines have been measured along lines of sight close to the Plasma Grid, and have been interpreted with the ADAS package to get the desired information. This work will describe the diagnostic hardware, the analysis method and the measured values of electron density and temperature, as function of the main source parameters (RF power, pressure, bias voltage and magnetic filter field). The main results show that not only electron density but also electron temperature increase with RF power; both decrease with increasing magnetic filter field. Variations of source pressure and plasma grid bias voltage appear to affect only electron temperature and electron density, respectively.Comment: 7 pages 4 figures. Contributed paper for the NIBS 2016 conference. Accepted manuscrip

Reconfigurations in the university academic area and its impact on strategic management

El presente trabajo es el resultado de una investigación sobre los condicionantes que inciden en la toma de decisiones estratégicas del área académica universitaria. A partir de la realización de entrevistas en profundidad a informantes claves de la Facultad de Ciencias Económicas y Sociales de la Universidad Nacional de Mar del Plata, la cual constituye el foco de estudio, se ha considerado relevante exponer aquí los resultados de la percepción que tienen los miembros sobre la priorización de tales procesos decisorios. Se analizará a la luz del contexto actual de la Universidad Pública Argentina, del cual emergen múltiples variables situacionales que complejizan y afectan la calidad de la gestión estratégica. El objetivo es poder generar información relevante que contribuya a la mejora en la planificación estratégica de la planta docente y permita optimizar la sostenibilidad de las políticas universitarias. Se pretenderá resaltar la importancia de invertir tiempo en decisiones que tienen un profundo impacto de largo plazo en todos los actores, como así también en establecer lineamientos claros que aseguren el desarrollo integral de la profesión docente.This work is the result of a study about conditioning factors in the strategic decision making processes at the university academic area. From in-depth interviews, made to important actors of the Faculty of Economic and Social Sciences of the National University of Mar del Plata, which is the focus of study, it has considered important to show here the results of the perceptions that members have about the prioritization of such decision-making processes. They will be analyzed in light of the changes that the Public University of Argentina is experiencing, where new variables emerge and make it difficult to think in the long term. The objective is to produce relevant information that helps strategic management of the teaching team and make possible the sustainability of university policies. It pretends to show the importance of investing time on decisions that have profound long-term impact on all university actors. It is also important to establish clear guidelines that ensure the complete development of teaching profession.Facultad de Ciencias Económica

Reconfigurations in the university academic area and its impact on strategic management

El presente trabajo es el resultado de una investigación sobre los condicionantes que inciden en la toma de decisiones estratégicas del área académica universitaria. A partir de la realización de entrevistas en profundidad a informantes claves de la Facultad de Ciencias Económicas y Sociales de la Universidad Nacional de Mar del Plata, la cual constituye el foco de estudio, se ha considerado relevante exponer aquí los resultados de la percepción que tienen los miembros sobre la priorización de tales procesos decisorios. Se analizará a la luz del contexto actual de la Universidad Pública Argentina, del cual emergen múltiples variables situacionales que complejizan y afectan la calidad de la gestión estratégica. El objetivo es poder generar información relevante que contribuya a la mejora en la planificación estratégica de la planta docente y permita optimizar la sostenibilidad de las políticas universitarias. Se pretenderá resaltar la importancia de invertir tiempo en decisiones que tienen un profundo impacto de largo plazo en todos los actores, como así también en establecer lineamientos claros que aseguren el desarrollo integral de la profesión docente.This work is the result of a study about conditioning factors in the strategic decision making processes at the university academic area. From in-depth interviews, made to important actors of the Faculty of Economic and Social Sciences of the National University of Mar del Plata, which is the focus of study, it has considered important to show here the results of the perceptions that members have about the prioritization of such decision-making processes. They will be analyzed in light of the changes that the Public University of Argentina is experiencing, where new variables emerge and make it difficult to think in the long term. The objective is to produce relevant information that helps strategic management of the teaching team and make possible the sustainability of university policies. It pretends to show the importance of investing time on decisions that have profound long-term impact on all university actors. It is also important to establish clear guidelines that ensure the complete development of teaching profession.Facultad de Ciencias Económica

Characterization of Cs-free negative ion production in the ion source SPIDER by Cavity Ring-Down Spectroscopy

The Neutral beam Injectors of the ITER experiment will be based on negative ion sources for the generation of beams composed by 1 MeV H/D particles. The prototype of these sources is currently under testing in the SPIDER experiment, part of the Neutral Beam Test Facility of Consorzio RFX, Padua, Italy. Among the targets of the experimentation in SPIDER, it is of foremost importance to maximize the beam current density extracted from the source acceleration system. The SPIDER operating conditions can be optimized thanks to a Cavity Ring-down Spectroscopy diagnostic, which is able to give line-integrated measurements of negative ion density in proximity of the acceleration system apertures. Regarding the diagnostic technique, this work presents a phenomenon of drift in ring down time measurements, which develops in a time scale of few hours. This issue may significantly affect negative ion density measurements for plasma pulses of 1 h duration, as required by ITER. Causes and solutions are discussed. Regarding the source performance, this paper presents how negative ion density is influenced by the RF power used to sustain the plasma, and by the magnetic filter field present in SPIDER to limit the amount of co-extracted electrons. In this study, SPIDER was operated in hydrogen and deuterium, in Cs-free conditions.Comment: 9 pages, 5 figures. Accepted manuscript of a published articl

Reconfigurations in the university academic area and its impact on strategic management

El presente trabajo es el resultado de una investigación sobre los condicionantes que inciden en la toma de decisiones estratégicas del área académica universitaria. A partir de la realización de entrevistas en profundidad a informantes claves de la Facultad de Ciencias Económicas y Sociales de la Universidad Nacional de Mar del Plata, la cual constituye el foco de estudio, se ha considerado relevante exponer aquí los resultados de la percepción que tienen los miembros sobre la priorización de tales procesos decisorios. Se analizará a la luz del contexto actual de la Universidad Pública Argentina, del cual emergen múltiples variables situacionales que complejizan y afectan la calidad de la gestión estratégica. El objetivo es poder generar información relevante que contribuya a la mejora en la planificación estratégica de la planta docente y permita optimizar la sostenibilidad de las políticas universitarias. Se pretenderá resaltar la importancia de invertir tiempo en decisiones que tienen un profundo impacto de largo plazo en todos los actores, como así también en establecer lineamientos claros que aseguren el desarrollo integral de la profesión docente.This work is the result of a study about conditioning factors in the strategic decision making processes at the university academic area. From in-depth interviews, made to important actors of the Faculty of Economic and Social Sciences of the National University of Mar del Plata, which is the focus of study, it has considered important to show here the results of the perceptions that members have about the prioritization of such decision-making processes. They will be analyzed in light of the changes that the Public University of Argentina is experiencing, where new variables emerge and make it difficult to think in the long term. The objective is to produce relevant information that helps strategic management of the teaching team and make possible the sustainability of university policies. It pretends to show the importance of investing time on decisions that have profound long-term impact on all university actors. It is also important to establish clear guidelines that ensure the complete development of teaching profession.Facultad de Ciencias Económica