During a previous metrology measurement, the torlon rings of RFXmod2 were found to be slightly shorter than the nominal design. This gave rise to a difficult mounting on the PSS. Therefore, kapton spacers to be inserted between the torlon segments of each ring of RFXmod2 were designed and tested.

The RFX-mod experiment (formerly RFX [1]) is the largest Reversed Field Pinch [2] device in operation, that proved the feasibility of active stabilization of MHD instabilities (Resistive Wall Modes) [3], by enclosing the plasma in a combination of a passive stabilizing shell and a real-time controlled network of saddle coils [4], as originally conceived by J.D. Lawson [5] and later proposed by C.M. Bishop [6]. The core of the experiment was the toroidal vacuum vessel (Inconel 625, Rmajor = 2.0 m, rminor = 0.5 m, thickness = 30 mm), surrounded by a Copper shell (3 mm thick) for the passive stabilization of the MHD instabilities, both enclosed in a toroidal support structure (AISI 304 L, 47 mm thick) embedding a set of 4 × 48 saddle coils for the active MHD control (Fig. 1). The flexibility of the RFX-mod device allowed exploring magnetic configurations at different levels of the safety factor [7]. In RFP regimes, especially at high plasma currents, transitions to improved confinement helical states [8], similar to theoretical and numerical predictions [9], have been observed and characterized. Thanks to active control, stable very-low q (edge q<2) ohmic tokamak discharges have been routinely obtained [10]; moreover, ultra-low q regimes have been studied [8]. H-mode in tokamak plasmas have been obtained by means of a polarized insertable electrode [11]. The properties of RFP plasmas in RFX-mod have been found to be influenced in several ways by the residual MHD instabilities (Tearing Modes), whose amplitude and phase non-linear dynamics are strongly influenced by the characteristics of the toroidal complex containing the plasma. In particular, the very high resistivity of the Inconel vacuum vessel (actually the highest among all RFP devices) was such that Tearing Modes were locked to the wall in all plasma current regimes explored by RFX. RFX-mod active control allowed mitigating the localized interaction due the bulging induced by wall locking of tearing modes and very low plasma current campaigns (Ip<150kA) revealed spontaneous fast rotating tearing modes regimes. On the other hand, the high proximity of the vessel plays an important role in the very-low q ohmic tokamak operations [8]. Having identified the limitations posed by its toroidal complex [12], a substantial modification, of the RFX experiment has been proposed, named RFX-mod2 being the second major modification since its original design. The implementation of the proposed machine modification, involving the components of the whole vessel complex (Fig. 1), has been developed in virtue of an industrial innovation project co-funded by an Italian local authority (Regione Veneto) in the framework of the 2014-2020 European Regional Development Fund. The project, aimed at the development of technologies and innovation of industrial processes for the manufacturing of equipment for energy and environment, has been carried out in partnership between Consorzio RFX (research institution in charge of the conceptual design) and three manufacturing industries with specific competences necessary for the development of the detailed design: o Vacuum vessel and UHV components manufacturing processes (Zanon Pressure Equipment srl, now Brembana & Rolle spa). o Material surface treatments (Alca Technology srl). o Metal additive manufacturing (Sisma spa).

The preliminary assembly of the copper shell (PSS) executed during 2022 pointed out several critical issues, in particular the difficulty to keep the PSS on the temporary support frames with the shape close to the nominal one, making hard the installation of the 72 stiffening torlon rings. In order to guarantee the PSS shape close to the nominal position, a system of pushers to be installed on the temporary support frames has been proposed. This document describes the test of two proposals for the pushers (one 'commercial' and one 'custom') and the design of the selected solution ('custom') based on the results of the test.

Il presente rapporto di prova descrive i risultati delle prove meccaniche ed elettriche eseguite su tre bussole in vetroresina del giunto verticale (poloidale) della VTSS, eseguite presso le officine ZPE in conformità alle specifiche tecniche <RFXmod2_TS_011> [1].

In previsione di effettuare misure e rilievi propedeutici allo smontaggio della BEAM SOURCE di SPIDER e per altre attività di misura dentro il bunker, si vuole controllare la incertezza di misura che ha la rete USMN (Unified Spatial Metrology Network) di SPIDER realizzata a settembre del 2017. Questa rete è composta fisicamente da 40 punti fiduciali realizzati con altrettante boccole calibrate con il foro Ø8 H7, sulle quali si inserisce il portatarget con offset 25,00 mm su cui si aggancia il target SMR, Spherically Mounted Retroreflectors, da Ø1,5": 16 boccole sono saldate all'interno del vessel di Spider e 24 fissate sui muri e il pavimento del bunker stesso. Poi mediante una serie di misurazioni delle coordinate X, Y, Z di questi punti con laser tracker (più di 300) da 15 postazioni diverse, e la successiva elaborazione con il software Spatial Analyzer, si ottiene la rete USMN.

La nota tecnica descrive cosa offre il mercato per prodotti metrologici, qual'è l'attuale dotazione del Consorzio RFX, cosa possiamo fare e non fare con l'attruale strumentazione, l'indagine di mercato sulla strumentazione e le conclusioni in merito alle prestazioni strumentali, all'utilizzo e al costo degli strumenti.

This document presents the On-Site Acceptance Test Report and Certifications of the Rotating Platform. It represents the Deliverable ST4.5 of the contract F4E OFC 582 TO#02 about the procurement and installation of the Rotating Platform (Subtask 4).

SPIDER is the prototype ion source for ITER Heating and Diagnostic Neutral Beams. To investigate the phase-space distribution of its beamlets, an Allison type emittance scanner was developed. This kind of diagnostic is widely used in ion sources for high-energy accelerators, but has never been employed in fusion-relevant ion sources. Its measurements will assess the optics properties of the beamlets of a large negative ion source, providing a local measurement of their phase-space structure, and they will be useful to validate numerical models. This paper presents the experimental setup of the diagnostic, describing the detector, its integration in SPIDER, the handling system and the control electronics. The effectiveness of the design of the detector Faraday cup to repel secondary electrons is experimentally proven. Finally, the emittance measurements obtained in a dedicated test facility are also reported and compared with ray tracing simulations.

Nell'ambito del progetto RFX-mod2 / MIAIVO è prevista la realizzazione di una nuova struttura di supporto isolante della scocca stabilizzatrice in rame dell'esperimento (Passive Stabilizing Shell -PSS) composta da 72 anelli,che dovranno sorreggere la scocca all'interno della nuova camera da vuoto.Viste le particolari condizioni operative, tale struttura deve essere realizzata con materiali non convenzionali. Nello specifico è stato selezionato il materiale "superpolimero" TORLON-PAI che nelle geometrie richieste richiede la realizzazione dei componenti mediante stampaggio ad iniezione.Prima della realizzazione dei "componenti di serie", che verranno installati nell'esperimento RFX-mod2, è stato necessario realizzare lo "Stampo" e le relative "Attrezzature", per il successivo stampaggio ad iniezione, ed una significativa "Campionatura" per validare il processo di realizzazione.

This document presents the On-Site Assembly and Installation Report of the Rotating Platform. It represents the Deliverable ST4.4 of the contract F4E OFC 582 TO#02 about the procurement and installation of the Rotating Platform (Subtask 4).

The ITER Neutral Beam Test Facility, in an advanced stage of construction in Padova, includes the installation, tests, and optimization of the full prototype of the ITER Heating Neutral Beams injector (HNBs), named MITICA. The MITICA Neutral Beam Injector will host its main components in a SS304L vacuum vessel composed of two modules, connected between them on site: the Beam Source Vessel (cubic shape of 5 m side and 67 tons weight) containing the Beam Source and the Beam Line Vessel (section 4.5 m x 4.5 m, length 11 m and 76 tons weight) containing the Beam Line Components and the Cryopumps. The manufacturing is described, going through the FE analyses performed to assess the structural integrity, the materials selection, the welding qualifications, the implementation of the double barrier sealings and the control of the deformations. The Factory Acceptance Tests of the individual vessels are presented, including their Helium Leak Tests. The two vessels have been assembled on-site inside the MITICA bio-shield. The main outcomes of on-site final assembly and Site Acceptance Tests are described. Both the vessels have been detail designed, manufactured, installed and tested by De Pretto Industrie, from Schio, (VI) Italy, supporting fusion technology's applications from more than 50 years. The design and the technical support were provided by Consorzio RFX, while the procurement was managed by Fusion For Energy.

We present the development and first use of a set of movable electrostatic probes on the full-scale ITER heating neutral beam prototype negative-ion source SPIDER. The probes access the ion source plasma from the multi-aperture accelerator aiming at the study of the plasma formation and expansion from the RF drivers through the transverse magnetic filter. The magnetic filter separates the relatively high electron-temperature region for plasma formation and hydrogen dissociation form the negative-ion extraction region in which low electron-temperature is required to avoid negative-ion destruction, but also causes non-uniformities and drifts in the large plasma discharge which will be studied by this setup. The set of electrostatic probes encompasses eight RF-compensated Langmuir probes, one double probe, one Mach probe for the assessment of plasma drift velocities, and two gridded retarding field energy analyzers to measure the positive-ion energy distribution function. Electric aspects as well as mechanical constraints given by the large in-vacuum movable structure, and thermal requirements of these relatively heat-flux components made the design challenging. Prototyping and commissioning of the measurement system is discussed offering examples of measured characteristics with the various probes.

#LoSapevateChe serve un sistema di punti fiduciali e segnali laser per poter posizionare, con estrema precisione, i componenti di MITICA, il prototipo dell'iniettore di neutri di ITER.

Giant negative-ion sources for fusion plasma heating are optimized to provide, by a peculiar magnetic topology in the expansion region, a separation between a relatively high electron-temperature region for plasma formation and hydrogen dissociation, and a beam extraction region in which low electron-temperature is required to avoid negative-ion destruction. The full-scale ITER neutral beam ion-source prototype SPIDER is the largest RF-driven negative ion source in operation, and it exhibits non-uniformities and drifts in the large expansion region from the eight RF drivers. A direct measurement of the plasma density and electron temperature in the expansion and extraction region as a function of the operational parameters is therefore required to correlate negative-ion beam uniformity to the operational parameters. The main operational parameters affecting plasma expansion and uniformity are the gas pressure, the perpendicular magnetic field strength, and the electric bias of ion source surfaces. This paper describes the development of a set of movable electrostatic probes that are used to measure axial profiles of plasma parameters, entering the ion source from the electrode apertures of the ion accelerator towards the RF drivers. The set of electrostatic probes encompasses eight RF-compensated Langmuir probes, one double probe, one triple probe for relatively high-frequency measurements, one Mach probe for the assessment of plasma drift velocities, and two gridded retarding field energy analyzers to measure the positive-ion energy distribution function. The mechanical constraints given by the experimental setup, based on a large in-vacuum movable structure with multiple probes entering from small apertures and required to scan about 400 mm, the thermal requirements of these relatively heat-flux components, and the electrical aspects, made the design challenging for the limited allowable dimensions. Prototyping and commissioning of the measurement system is also discussed. Examples of measured axial profiles with the various probes used in SPIDER will be presented.

The ITER Neutral Beam Test Facility, in an advanced construction in Padova, includes the installation, tests, and optimization of the full prototype of the ITER Heating Neutral Beams injectors (HNBs), named MITICA. The MITICA Neutral Beam Injector will host its main items in a SS304L vacuum vessel composed of two modules, connected between them on site: the Beam Source Vessel (cubic of 5 m side and 67 tons weight) containing the ion Beam Source and the Beam Line Vessel (section 4.5 m x 4.5 m, length 11 m and 76 tons weight) containing the Beam Line Components and the Cryopumps. The project requirements were transferred in the manufacturing design and in the fabrication process of these large vessels produced through welding and machining. The following steps were in particular carried out before and during manufacturing: o FE analyses to assess the structural integrity and limited deformations under vacuum loading conditions (leading to ribs reinforcement) o materials selection suitable for the specific application o qualification of special processes (welding and NDE) to ensure control of welding distortions and leak tight joints o implementation of double barrier sealings for the most critical connections o control of deformations under vacuum loads comparing displacement measurements with results of FE analyses. The Factory Acceptance Tests of the individual vessels are presented, including their Helium Leak Tests. The two vessels have been assembled on-site inside the MITICA bio-shield. They have been connected through a double sealing barrier composed of elastomer and a leak tight welded flange connection, previously qualified at the factory. The main outcomes of on-site final assembly and Site Acceptance Tests are described. Both vessels have been manufactured, installed and tested by De Pretto Industrie; the design and the technical support were provided by Consorzio RFX, while the procurement was managed by F4E.

SPIDER experiment is operating at the PRIMA site in Padova (I) since June 2018, with the aim of testing and optimizing the negative ion source prototype for ITER Heating Neutral Beam Injectors. In the first operational phase it was discovered that, as the in-vessel hydrogen pressure exceeds the design requirements, discharges occur on the back of the radio frequency source. A specific operational campaign allowed defining a threshold below which the discharge probability is strongly reduced. In order to extend the operational range of the source pressure above the nominal value, while a significant upgrade of the vacuum pumping system is designed and realized, it was decided to proceed with the SPIDER operations by applying a temporary solution. A mask was installed on the beam source plasma grid, closing most of its apertures, in order to reduce the gas conductance between the inside of the radio frequency source and the surrounding volume. At first only 80 over 1280 apertures are left open, with a specific layout properly arranged so as to guarantee the possibility to diagnose the beam characteristics and to evaluate its uniformity. In the paper the plasma grid masking system is described. Finally, an overview of the behavior of plasma grid mask during SPIDER operations is given.

This document presents the Factory Acceptance Test Plan for the procurement of the Rotating Platform. The FAT Plan is part of the deliverable D-FR ADP & Final Report of the contract F4E OFC 582 TO#02 about the procurement and installation of the Rotating Platform (Subtask 4).

This document presents the On-Site Acceptance TestPlanfor the Rotating Platform. It represents the deliverable ST4.3 of the contract F4EOFC 582 TO#02 about the procurement and installation of the Rotating Platform (Subtask 4).

This document presents the On-Site Assembly and Installation Plan for the Rotating Platform. It represents the deliverable ST4.2 of the contract F4E OFC 582 TO#02 about the procurement and installation of the Rotating Platform (Subtask 4).