A wire calorimeter for the SPIDER beam: Experimental tests and feasibility study

Pasqualotto, R.; Serianni, G.; Mario, I.; Veltri, P.; Zanini, M.; Cervaro, V.; Fasolo, D.

doi:10.1063/1.4916477

Cited by 7 publications

(5 citation statements)

References 14 publications

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“…Observing the tungsten-wire calorimeter by a visible camera, a qualitative image of the beam can be obtained. By numerical modelling and laboratory tests it was surmised [119] that, upon careful calibration by electrical current and by zooming so that the camera pixels fall inside the wires, it is possible to obtain a quantitative measurement of the 2D energy flux associated to the impinging beam. The same paper describes a preliminary study regarding a similar system for SPIDER.…”

Section: Measurement Of Beam Energy Flux By Direct Interceptionmentioning

confidence: 99%

Neutralisation and transport of negative ion beams: physics and diagnostics

Serianni¹,

Agostinetti²,

Agostini³

et al. 2017

New J. Phys.

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Neutral beam injection is one of the most important methods of plasma heating in thermonuclear fusion experiments, allowing the attainment of fusion conditions as well as driving the plasma current. Neutral beams are generally produced by electrostatically accelerating ions, which are neutralised before injection into the magnetised plasma. At the particle energy required for the most advanced thermonuclear devices and particularly for ITER, neutralisation of positive ions is very inefficient so that negative ions are used. The present paper is devoted to the description of the phenomena occurring when a high-power multi-ampere negative ion beam travels from the beam source towards the plasma. Simulation of the trajectory of the beam and of its features requires various numerical codes, which must take into account all relevant phenomena. The leitmotiv is represented by the interaction of the beam with the background gas. The main outcome is the partial neutralisation of the beam particles, but ionisation of the background gas also occurs, with several physical and technological consequences. Diagnostic methods capable of investigating the beam properties and of assessing the relevance of the various phenomena will be discussed. Examples will be given regarding the measurements collected in the small flexible NIO1 source and regarding the expected results of the prototype of the neutral beam injectors for ITER. The tight connection between measurements and simulations in view of the operation of the beam is highlighted. operating in the existing tokamaks. Consequently, PRIMA, the ITER Neutral Beam Test Facility [2], was set up to constitute a test-bed, where the solutions to all the issues related to the achievement of full performances in the heating NBI system for ITER are going to be addressed and optimised, particularly regarding critical aspects like density and uniformity of the extracted negative ion current, high voltage holding and heat loads on the components [3]. Megavolt ITER Injector Concept Advancement (MITICA) is the full-scale prototype of the ITER NBIs [4]; it includes an RF-driven plasma source for the production of negative ions and should operate at a pressure as low as 0.3 Pa in hydrogen or deuterium gasses. The negative ions are produced on the surface of the grid (Plasma Grid, PG) that closes the plasma region; their production is enhanced thanks to a thin caesium layer continuously deposited over the PG by evaporation. Negative ions are extracted through the 1280 apertures in the PG by application of a suitable positive voltage to the extraction grid (EG), located just downstream of the PG. The RF plasma source operates at an applied electric potential of about −1 MV. Five additional acceleration grids (AG1, AG2, AG3, AG4, GG), at intermediate electric potential increasing by 200 kV steps, are located downstream with respect to the EG, thus constituting a 5-stage electrostatic accelerator. The resulting negative ion beam at 1 MeV, after passing through a gas cell neutraliser and an electro...

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Section: Measurement Of Beam Energy Flux By Direct Interceptionmentioning

confidence: 99%

Neutralisation and transport of negative ion beams: physics and diagnostics

Serianni¹,

Agostinetti²,

Agostini³

et al. 2017

New J. Phys.

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show abstract

“…castellated graphite tiles [24]), or moving to a completely different concept, a tungsten wire calorimeter, i.e. an array of parallel tungsten wires exposed to the beam, emitting blackbody radiation with a spatial profile sufficiently resolved to distinguish the single beamlet and to provide information on the beam parameters [25] (figure 8). The analysis showed that such solutions achieve lower resolution or strength compared to CFC tiles, hence they will not be installed on SPIDER.…”

Section: Jinst 12 C10009mentioning

confidence: 99%

A suite of diagnostics to validate and optimize the prototype ITER neutral beam injector

Pasqualotto¹,

Agostini²,

Barbisan³

et al. 2017

J. Inst.

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in the present paper with a focus on their rationale, key solutions and most original and effective implementations. K: Beam-line instrumentation (beam position and profile monitors; beam-intensity monitors; bunch length monitors); Plasma diagnostics -interferometry, spectroscopy and imaging; Beam dynamics; Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS))

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“…castellated graphite tiles), or moving to a completely different concept, a tungsten wire calorimeter, i.e. an array of parallel tungsten wires exposed to the beam, emitting blackbody radiation with a spatial profile sufficiently resolved to distinguish the single beamlet and to provide information on the beam parameters [18].…”

Section: Spider Diagnosticsmentioning

confidence: 99%

“…Simulation and analysis codes have been developed for most diagnostics, like BES spectra modeling and analysis [8], tomographic inversion with regularization [9], CRDS and laser absorption simulations, thermal analyses of STRIKE tiles and of wire calorimeter [17] [18].…”

Section: Spider Diagnosticsmentioning

confidence: 99%

Progress On Diagnostics Of The Iter Neutral Beam Test Facility

Pasqualotto¹,

Agostini²,

Barbisan³

et al. 2016

Proceedings of 1st EPS Conference on Plasma Diagnostics — PoS(ECPD2015)

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ITER operation relies on heating neutral beam injectors (HNB) based on negative ion deuterium beams accelerated at 1 MeV, with up to one hour 17 MW power, uniform intensity and low divergence. A neutral beam test facility is being built at Consorzio RFX to demonstrate the feasibility of a prototype injector with such demanding specifications and to optimize its performances. It comprises SPIDER, a 100 kV negative hydrogen/deuterium RF source, full size prototype of the HNB source, and MITICA, a prototype of the full HNB. The diagnostics for SPIDER and MITICA are essential to qualify and optimize the HNB for ITER and to assess the information on source and beam obtainable with the reduced set of the HNB diagnostics. Main parameters are measured with different complementary techniques to exploit the combination of their specific features. In the source the still open issues of cesium dynamics, negative ion generation and uniformity are investigated with a set of electrostatic probes, with optical emission spectroscopy, laser absorption for neutral cesium density and cavity ring down spectroscopy for negative ion density. The beam profile uniformity and its divergence will be studied with beam emission spectroscopy, visible tomography, neutron imaging and a special calorimeter made of carbon tiles which can achieve a spatial resolution of few millimetres. All components heated by beam power load will be monitored with a large set of thermocouples behind the heated surfaces and on the cooling water circuits. The test facility will also be the natural choice for hosting experiments on innovative concepts for DEMO HNBs, e.g. more efficient neutralization techniques and cesium free source operation.

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A wire calorimeter for the SPIDER beam: Experimental tests and feasibility study

Cited by 7 publications

References 14 publications

Neutralisation and transport of negative ion beams: physics and diagnostics

Neutralisation and transport of negative ion beams: physics and diagnostics

A suite of diagnostics to validate and optimize the prototype ITER neutral beam injector

Progress On Diagnostics Of The Iter Neutral Beam Test Facility

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