Design, manufacture and factory testing of the Ion Source and Extraction Power Supplies for the SPIDER experiment

Bigi, M.; Rinaldi, Luigi; Simon, M.; Sita, L.; Taddia, Giuseppe; Carrozza, Saverino; Decamps, Hans; Luchetta, A.; Meddour, Abdelraouf; Moressa, Modesto; Morri, Cristiano; Tanzi, Antonio Musile; Recchia, M.; Wagner, Uwe; Zamengo, A.; Toigo, V.

doi:10.1016/j.fusengdes.2015.06.163

Cited by 36 publications

(10 citation statements)

References 13 publications

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“…A lateral view of the SPIDER negative ion source is schematized in Figure 1a. Following a modular concept, eight cylindrical ICP plasma sources (called plasma drivers) are present, arranged in four rows and two columns; each row of sources is powered by a separate RF generator (max 200 kW at 1 MHz), labelled RF1-RF4 [19]. All the drivers let the plasma diffuse in a common expansion chamber, towards the acceleration system, which in SPIDER is composed by three grids: Plasma Grid (PG), Extraction Grid (EG) and Acceleration Grid (AG).…”

Section: The Spider Ion Sourcementioning

confidence: 99%

Negative ion density in the ion source SPIDER in Cs free conditions

Barbisan¹,

Agnello²,

Casati³

et al. 2022

Plasma Phys. Control. Fusion

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The SPIDER experiment, operated at the Neutral Beam Test Facility of Consorzio RFX, Padua, hosts the prototype of the H-/D- ion source for the ITER neutral beam injectors. The maximization of the ion current extracted from the source and the minimization of the amount of co-extracted electrons are among the most relevant targets to accomplish. The Cavity Ring-Down Spectroscopy diagnostic measures the negative ion density in the source close to the plasma grid (the plasma-facing grid of the ion acceleration system), so to identify the source operational parameters that maximize the amount of negative ions which can be extracted. In this study SPIDER was operated in hydrogen and deuterium in Cs-free conditions, therefore negative ions were mostly produced by reactions in the plasma volume. This work shows how the magnetic filter field and the bias currents, present in SPIDER to limit the amount of co-extracted electrons, affect the density of negative ions available for extraction. The results indicate that the magnetic filter field in front of the acceleration system should be set between about 1.6 mT, condition that maximizes the density of available negative ions, and about 3.2 mT, condition that minimizes the ratio of electron current to ion current. The negative ion density also resulted to be maximized when the plasma grid and its surrounding bias plate was positively biased against the source body with a total current in the range 0 A÷100 A. The paper shows also how much, in Cs-free conditions, the electric fields in the acceleration system can affect the density of negative ions in the source, close to the plasma grid apertures.

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Section: The Spider Ion Sourcementioning

confidence: 99%

Negative ion density in the ion source SPIDER in Cs free conditions

Barbisan¹,

Agnello²,

Casati³

et al. 2022

Plasma Phys. Control. Fusion

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“…For the purpose of this study, it is necessary to consider the electrical connections in the beam source, the arrangement of conductors in the transmission line [7] and the layout of ISEPS [8] (Ion Source and Extraction Power Supplies) installed inside the air-insulated HVD, as represented in Figure 1.…”

Section: Spider Electrical Systemmentioning

confidence: 99%

Study of RF Stray Currents in ITER Neutral Beam Test Facilities

et al. 2021

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The operation of SPIDER (Source for the Production of Ions of Deuterium Extracted from Radio-frequency plasma), full-scale prototype of ITER NBI (Neutral Beam Injector) radio-frequency ion source, pointed out deleterious effects caused by stray Radio-Frequency (RF) currents flowing in the electrical equipment not included in the RF power system. MITICA (Megavolt ITER Injector and Concept Advancement), the full-scale prototype of ITER NBI, is characterized by a similar design in terms of layout of the power supplies and connections to the beam source; thus, it is expected to be subject to the RF stray currents problem. SPIDER RF system is composed of four RF generators, four coaxial lines and four RF loads. Each RF generator is rated for operation at 200 kW in the frequency range 0.9 ÷ 1.1 MHz. The power is delivered to the four loads via as many RF coaxial lines, housed inside a multiconductor transmission line. Each load consists of a capacitive matching network and two plasma drivers in series. Due to the presence of stray connections at the generator and beam-source side (e.g., parasitic capacitances), unwanted RF currents can flow through alternative paths and negatively affect the components not intended for transmission of RF power, the output stages of power supplies and several diagnostics installed in the High-Voltage Deck (HVD) and at the beam source. This paper presents the development of a circuital model used to estimate the RF stray currents in SPIDER electrical system; the understanding of this phenomenon and the development of a model with predictive capabilities is fundamental for the assessment of the performance of both SPIDER and MITICA and, in general, of alternative RF system layouts with respect to the stray currents issue.

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“…Two Power Supply (PS) systems provide the electric power to the SPIDER experiment: the Ion Source and Extraction Power Supply system (ISEPS) and the Acceleration Grid Power Supply system (AGPS). ISEPS is a collection of power supplies for generation and extraction of negative ions [12], comprising: EG power supply (-12kV, 140A); 4 tetrode-based push-pull oscillators as RF generators (0.9÷1.1MHz 200kW on 50Ω load each), each feeding two drivers; PG filter power supply (5kA, 15V). AGPS (procured in-kind by ITER India) provides the high voltage for ion acceleration (-96kV, 75A) [13].…”

Section: Spidermentioning

confidence: 99%

SPIDER in the roadmap of the ITER neutral beams

Serianni

Toigo

Bigi

et al. 2019

Fusion Engineering and Design

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To reach fusion conditions and control plasma configuration in ITER, a suitable combination of additional heating and current drive systems is necessary. Among them, two Neutral Beam Injectors (NBI) will provide 33MW hydrogen/deuterium particles electrostatically accelerated to 1MeV; efficient gas-cell neutralisation at such beam energy requires negative ions, obtained by caesium-catalysed surface conversion of atoms inside the ion source. As ITER NBI requirements have never been simultaneously attained, a Neutral Beam Test Facility (NBTF) was set up at Consorzio RFX (Italy), including two experiments. MITICA is the full-scale NBI prototype with 1MeV particle energy. SPIDER, with 100keV particle energy, aims at testing and optimising the full-scale ion source: extracted beam uniformity, negative ion current density (for one hour) and beam optics (beam divergence <7mrad; beam aiming direction within 2mrad). This paper outlines the worldwide effort towards the ITER NBI realisation: the main results of the ELISE facility (IPP-Garching, Germany), equipped with a half-size source, are described along with the status of MITICA; specific issues are investigated by small specific facilities and by joint experiments at QST and NIFS (Japan). The SPIDER experiment, just come into operation, will profit from strong modelling activities, to simulate and interpret experimental scenarios, and from advanced diagnostic instruments, providing thorough plasma and beam characterisation. Finally, the results of the first experiments in SPIDER are presented, aimed at a preliminary source plasma characterisation by plasma light detectors and plasma spectroscopy.

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Design, manufacture and factory testing of the Ion Source and Extraction Power Supplies for the SPIDER experiment

Cited by 36 publications

References 13 publications

Negative ion density in the ion source SPIDER in Cs free conditions

Negative ion density in the ion source SPIDER in Cs free conditions

Study of RF Stray Currents in ITER Neutral Beam Test Facilities

SPIDER in the roadmap of the ITER neutral beams

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