Detailed design optimization of the MITICA negative ion accelerator in view of the ITER NBI

Agostinetti, P.; Aprile, D.; Antoni, V.; Cavenago, M.; Chitarin, G.; Esch, H.P.L. de; Lorenzi, A. De; Fonnesu, N.; Gambetta, G.; Hemsworth, R.; Kashiwagi, M.; Marconato, N.; Marcuzzi, D.; Pilan, N.; Sartori, E.; Serianni, G.; Singh, Manoj; Sonato, P.; Spada, E.; Toigo, V.; Veltri, P.; Zaccaria, P.

doi:10.1088/0029-5515/56/1/016015

Cited by 92 publications

(45 citation statements)

References 70 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During the final design phase, several innovative solutions for the achievement of MITICA full performance have been proposed by Consorzio RFX and adopted [44]. The most significant of these are the following:…”

Section: The Mitica Beam Sourcementioning

confidence: 99%

The PRIMA Test Facility: SPIDER and MITICA test-beds for ITER neutral beam injectors

Toigo¹,

Piovan²,

Bello³

et al. 2017

New J. Phys.

157

View full text Add to dashboard Cite

The ITER Neutral Beam Test Facility (NBTF), called PRIMA (Padova Research on ITER Megavolt Accelerator), is hosted in Padova, Italy and includes two experiments: MITICA, the full-scale prototype of the ITER heating neutral beam injector, and SPIDER, the full-size radio frequency negative-ions source. The NBTF realization and the exploitation of SPIDER and MITICA have been recognized as necessary to make the future operation of the ITER heating neutral beam injectors efficient and reliable, fundamental to the achievement of thermonuclear-relevant plasma parameters in ITER. This paper reports on design and R&D carried out to construct PRIMA, SPIDER and MITICA, and highlights the huge progress made in just a few years, from the signature of the agreement for the NBTF realization in 2011, up to now-when the buildings and relevant infrastructures have been completed, SPIDER is entering the integrated commissioning phase and the procurements of several MITICA components are at a well advanced stage.

show abstract

Section: The Mitica Beam Sourcementioning

confidence: 99%

The PRIMA Test Facility: SPIDER and MITICA test-beds for ITER neutral beam injectors

Toigo¹,

Piovan²,

Bello³

et al. 2017

New J. Phys.

157

View full text Add to dashboard Cite

show abstract

“…The electrostatic deflection due to the beamlets having charge of the same time can be seen (topmost beamlet); details of the EG, together with the system of magnets (CESM and ADCM) devoted to dump the co-extracted electrons while minimally affecting the negative ions (see section 2.3); the PG aperture exhibits the so-called Pierce angle on the downstream side; on the upstream side the meniscus is sketched in red. downstream in the same gap where they are generated; the deflection of the negative ions is minimised by a suitable alternation of the polarity of the magnets (figure 1 [4]).…”

Section: Beam Formationmentioning

confidence: 99%

“…The paraxial approximation is possibly prone to large errors near the extraction region z=g; here z=0 is the extraction aperture plane and z n @0 the meniscus and axis intersection. For z=g the relation between r(z) and V(z) and electrode shapes is given by self-consistent space charge equilibria [31,33], which thus determine the starting conditions for r(z) and V(z) in equation (4).…”

Section: Space Charge Effectsmentioning

confidence: 99%

“…Many causes could determine misalignments between the beam and the aperture axes; some of them have mechanical origin, like the misalignments between apertures during grid realisation and installation [40] or the grid deformation induced by thermal loads. The first can be minimised by careful alignment of the electrodes, whereas the second can be addressed using dedicated thermal analyses [4,5]. Other sources of beam misalignment have a physical origin, such as the beam displacement due to the space charge repulsion by surrounding beamlets or under the influence of the magnets installed in the EG in order to deflect the co-extracted electrons (called co-extracted electrons suppression magnets, CESM).…”

Section: Beam Deflectionmentioning

confidence: 99%

See 1 more Smart Citation

Neutralisation and transport of negative ion beams: physics and diagnostics

Serianni¹,

Agostinetti²,

Agostini³

et al. 2017

New J. Phys.

View full text Add to dashboard Cite

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...

show abstract

“…Plasma formation in negative-ion beam systems, and the characteristics of such a plasma are of general interest especially for space charge compensation, plasma formation in common gas neutralizers. These aspects have direct implications in the ITER Heating Neutral Beam and the operation of the prototypes, SPIDER and MITICA [8,9], and also have important role in the studies for NBI systems in Demo. Normally, the presence of a secondary plasma is simply neglected in the simulation of beam transport and complete space charge compensation is assumed (see for instance [10,11] and references therein).…”

Section: Neutralization Efficiency and Beam-driven Plasma Neutralizersmentioning

confidence: 99%

Preliminary studies for a beam-generated plasma neutralizer test in NIO1

Sartori

Veltri

Balbinot

et al. 2017

AIP Conference Proceedings

Self Cite

View full text Add to dashboard Cite

show abstract

Detailed design optimization of the MITICA negative ion accelerator in view of the ITER NBI

Cited by 92 publications

References 70 publications

The PRIMA Test Facility: SPIDER and MITICA test-beds for ITER neutral beam injectors

The PRIMA Test Facility: SPIDER and MITICA test-beds for ITER neutral beam injectors

Neutralisation and transport of negative ion beams: physics and diagnostics

Preliminary studies for a beam-generated plasma neutralizer test in NIO1

Contact Info

Product

Resources

About