A conceptual system design study for an NBI beamline for the European DEMO

Hopf, C.; Starnella, G.; Harder, N. den; Heinemann, B.; Fantz, U.

doi:10.1016/j.fusengdes.2019.01.060

Cited by 10 publications

(5 citation statements)

References 17 publications

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“…The injector efficiency is the parameter which has to be improved most with respect to ITER (being currently only 26%), to make NBI a suitable solution for a fusion reactor. A crucial part of the NBI system determining the overall injector efficiency is the neutralizer [16], which has the task of neutralizing the negative ion beam. In ITER and present-day experiments (e.g.…”

Section: Introductionmentioning

confidence: 99%

Optimization-oriented modelling of neutral beam injection for EU pulsed DEMO

Vincenzi¹,

Agostinetti²,

Artaud³

et al. 2021

Plasma Phys. Control. Fusion

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Neutral beam injection (NBI) is one of the auxiliary power systems considered for the EU DEMO pulsed plasma ('DEMO1'). In this paper, we discuss the characteristics of optimized NBI in terms of the DEMO1 requirements, relating physics and engineering contexts in a novel parameter range compared to current NBI systems and in a larger plasma volume than ITER. Different injection options are investigated to account for various concepts discussed in the literature. The investigation is carried out using a wide range of sensitivity studies by means of the METIS 0.5D transport code and ASCOT Monte Carlo simulations of injected neutral-beam particles. This investigation has generated a series of recommendations for the NBI design, contributing to the system optimization process. We show how tangential injection aimed at the plasma core, with an energy ≳800 keV, is recommended to maintain high fusion power performance and fulfill the requirements for bulk heating. Compliance with engineering constraints on the NBI design, e.g., the least interference with breeding blanket modules or compatibility with solutions for the beamline components, imposes some restrictions when discussing the beam geometry. The minimum density at which an NBI can be safely operated without harmful shine-through losses is investigated for different injection energies and compared to the ITER case. The NBI operational window for DEMO is shown to be significantly extended to transient, low-density phases, also highlighting the importance of NBI systems designed for modular energy and power output. NBI can therefore sustain the plasma during a considerable portion of the transient phases, i.e., the current ramp-up and ramp-down phases. The final decision on the DEMO heating mix will be made on the basis of system operability and performance: the optimized NBI is shown to be a suitable and effective option for the EU DEMO inductive scenario.

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Section: Introductionmentioning

confidence: 99%

Optimization-oriented modelling of neutral beam injection for EU pulsed DEMO

Vincenzi¹,

Agostinetti²,

Artaud³

et al. 2021

Plasma Phys. Control. Fusion

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show abstract

“…The motivations to choose a design with four short beam blades, instead of two long beam blades as in the DEMO 2016 design [4], were that: • A more compact in height (or square-like) shape is more suitable both for a gas or a plasma neutralizer. In fact, for gas neutralizers the density distribution is more uniform with a compact shape, and for plasma neutralizers there are less plasma losses as the surface-to-volume ratio is smaller, as shown in [12].…”

Section: Updated Design Of the Demo Nbimentioning

confidence: 96%

RAMI evaluation of the beam source for the DEMO neutral beam injectors

Agostinetti

Franke

Fantz

et al. 2020

Fusion Engineering and Design

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“…Adapting an energy recovery system for the residual ions to this injector (with the ion source at −1 MV) [13] is of limited interest due to the additional complexity; this would require collecting ions (D + and D − ) at a high voltage (resp. +1 MV and −1 MV) involving two additional invasive bushings (at ±1 MV) and SF 6 transmission lines.…”

Section: Efficiency Of the Neutral Beam Linementioning

confidence: 99%

Towards a maintainable and high efficiency neutral beam system for future fusion reactors

et al. 2021

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Achievement of an economic fusion reactor imposes a high level of unprecedented requirements for neutral beam systems; the first one is the nuclear safety constraints which impose a prerequisite on the ease of access of all injector components to provide a preventive (and curative) maintenance by remote handling while maintaining reactor operation. In addition, the challenge is to develop high-power injectors with very high wall-plug efficiency (above 60%) that are able to operate in stable conditions over several months. There is a significant gap to bridge with respect to the present neutral beam systems, which are characterized by a low efficiency and by complex and long maintenance operations. Evidence that this injector concept does not offer adaptations to cope with the reactor requirements makes it clear that a new concept has to be addressed. An injector concept with modular sources at ground voltage is proposed. The concept makes remote maintenance of the injector components easier, where each source module can be replaced by a new one without breaking the vacuum and affecting injector conditioning. With the grounded and modular ion source, photoneutralization associated with energy recovery appears to be the best route capable of attaining the reactor requirements. This concept of a maintainable neutral beam system would provide a high heating power with a wall-plug efficiency above 70% and unprecedented features such as the capacity of producing temporal and spatial modulation of the beam power for a better control of the plasma stability. Up to now, photoneutralization feasibility studies already carried out on reduced-scale prototypes have not highlighted any showstoppers. Continuation of research and development in the years to come can pave the way towards the achievement of a first full-scale high-power cavity in the 1 MW range, and the realization of a multi-amperes (∼10 A) thin blade-like D− beam.

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A conceptual system design study for an NBI beamline for the European DEMO

Cited by 10 publications

References 17 publications

Optimization-oriented modelling of neutral beam injection for EU pulsed DEMO

Optimization-oriented modelling of neutral beam injection for EU pulsed DEMO

RAMI evaluation of the beam source for the DEMO neutral beam injectors

Towards a maintainable and high efficiency neutral beam system for future fusion reactors

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