°ÄÃÅÁùºÏ²Ê¸ßÊÖ

Neutral beam injection

Experts share research updates and progress

6 Nov 2023 - Xavier Litaudon, EUROfusion Project Leader/Preparation of °ÄÃÅÁùºÏ²Ê¸ßÊÖ Operation; CEA Research Director
A lucky set of circumstances brought together different experts on neutral beam injection for a few days at °ÄÃÅÁùºÏ²Ê¸ßÊÖ in October. Achieving the requirements for the °ÄÃÅÁùºÏ²Ê¸ßÊÖ neutral beam system in terms of power, energy, and pulse length simultaneously is a major challenge that benefits from open exchange and collaboration.
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Achieving the requirements for the °ÄÃÅÁùºÏ²Ê¸ßÊÖ neutral beam system in terms of power, energy, and pulse length is a major challenge that benefits from open exchange and collaboration. A cooperation agreement signed in 2020 between the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Organization, Consorzio RFX and EUROfusion formalizes the involvement of European experts in the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Neutral Beam Test Facility. (Xavier Litaudon, the author of this article, is fourth from right.)
To access, study and sustain burning plasmas on °ÄÃÅÁùºÏ²Ê¸ßÊÖ with a high-fusion-power amplification factor, the use of external heating and current drive system plays an essential role. In particular, °ÄÃÅÁùºÏ²Ê¸ßÊÖ will be equipped with two heating neutral beam injectors (with a provision of a third injector) and a neutral beam line for diagnostic purposes.

To support research and development on the °ÄÃÅÁùºÏ²Ê¸ßÊÖ neutral beam injection system prior to its procurement, the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Neutral Beam Test Facility was launched in 2012. The test facility includes two test beds—SPIDER, for the installation, optimization and operation of a full-size °ÄÃÅÁùºÏ²Ê¸ßÊÖ negative ion source, and MITICA, a full-size °ÄÃÅÁùºÏ²Ê¸ßÊÖ 1MV neutral beam injection system. The test facility is hosted at the Italian research laboratory Consorzio RFX in Padova, Italy, and is supported by the contributions of the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Organization, the European, Japanese and Indian Domestic Agencies, the EUROfusion consortium, and Consorzio RFX. Since 2019, a new agreement between Consorzio RFX and the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Organization has clarified roles and responsibilities as construction at the Neutral Beam Test Facility ends and operation in support of °ÄÃÅÁùºÏ²Ê¸ßÊÖ intensifies. 

Europe has been actively involved in the development of radiofrequency-driven ion source physics and technology from the start; in fact, °ÄÃÅÁùºÏ²Ê¸ßÊÖ's negative ion source is based on a technology that has evolved over several generations of prototypes at the Max Planck Institute for Plasma Physics in Garching, Germany. A cooperation agreement signed in 2020 between the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Organization, Consorzio RFX and EUROfusion now formalizes the involvement of European experts in the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Neutral Beam Test Facility by providing for the participation of up to 14 professionals per year. Additionally, EUROfusion is contributing up to 6 professionals per year to ongoing work at the reduced-size prototype ion sources as part of stepwise R&D leading to the achievement of °ÄÃÅÁùºÏ²Ê¸ßÊÖ's challenging neutral beam injection requirements.

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At °ÄÃÅÁùºÏ²Ê¸ßÊÖ Headquarters in late October, EUROfusion experts performing R&D for the °ÄÃÅÁùºÏ²Ê¸ßÊÖ neutral beam injection system at Consorzio RFX and IPP Garching had the opportunity to present their research to the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Neutral Beam Advisory Committee and the °ÄÃÅÁùºÏ²Ê¸ßÊÖ team.
°ÄÃÅÁùºÏ²Ê¸ßÊÖ is of key importance in the European research for the realization of fusion energy, as it aims to prove the scientific and technological feasibility of fusion as a future energy source. EUROfusion is contributing to the preparation of °ÄÃÅÁùºÏ²Ê¸ßÊÖ scientific exploitation and is leveraging the °ÄÃÅÁùºÏ²Ê¸ßÊÖ outcomes and lessons learned to inform the design of Europe's next-stage device, . In this context, a specific EUROfusion Work Package—"Preparation of °ÄÃÅÁùºÏ²Ê¸ßÊÖ Operation" (PrIO)—was created recently that includes R&D on the °ÄÃÅÁùºÏ²Ê¸ßÊÖ radiofrequency neutral beam ion sources, with both long-pulse discharge targets on the ELISE prototype in Garching and participation in the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Neutral Beam Test Facility.

On 26 and 27 October 2023, EUROfusion experts working to support the R&D for the °ÄÃÅÁùºÏ²Ê¸ßÊÖ neutral beam injection system at Consorzio RFX and IPP Garching had the occasion to convene at °ÄÃÅÁùºÏ²Ê¸ßÊÖ Headquarters at the same time as world experts who are part of the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Neutral Beam Advisory Committee (formed as part of the 2019 agreement). This was a unique opportunity to develop synergies and bridges between experts, as well as to present the work performed by the EUROfusion experts to the °ÄÃÅÁùºÏ²Ê¸ßÊÖ team and the committee. During a "teaser" session in the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Council room, experts gave two-minute summaries of their work. This was followed by a poster exposition in the lobby, a presentation of the °ÄÃÅÁùºÏ²Ê¸ßÊÖ Project, a worksite tour, a tour of France's WEST tokamak (next door to °ÄÃÅÁùºÏ²Ê¸ßÊÖ), and an informal dinner to continue the scientific exchange in a collaborative atmosphere. Because achieving the requirements for the °ÄÃÅÁùºÏ²Ê¸ßÊÖ neutral beam system in terms of power, energy, and pulse length is a major challenge, this type of "coming together of the minds" was appreciated by all.

The following is a list of the posters that were presented:

Riccardo Agnello: Investigation of SPIDER beam and plasma by multiple diagnostics
Riccardo Casagrande: Support to the design and testing of RF solid-state generators for NBTF and °ÄÃÅÁùºÏ²Ê¸ßÊÖ NBI
Caterina Cavallini: Support for operations, management, monitoring and verifications of NBTF cooling system
Nuno Cruz: Instrumentation & Control activities in support of the °ÄÃÅÁùºÏ²Ê¸ßÊÖ NB
Sylvestre Denizeau: Heating of SPIDER drivers during nominal operations: numerical estimation and comparison with calorimetry
Daniel López-Bruna: 3D calculations of RF inductive coupling in the drivers of SPIDER
Carlo Poggi: Diagnostics operation and development for SPIDER and MITICA
Basile Pouradier Duteil: Study and optimization of the use of caesium in large negative ion sources for nuclear fusion
Alastair Shepherd: Support of NBTF operations, diagnostics and beam current measurement
Luca Trevisan: Automation engineer for the NBTF
Niek den Harder: Beam studies in view of °ÄÃÅÁùºÏ²Ê¸ßÊÖ NBI systems
Adrian Heiler: Understanding Cs and work function dynamics at NNBI ion sources for °ÄÃÅÁùºÏ²Ê¸ßÊÖ
Guillermo Orozco: Mechanical engineer for neutral beam ion source
Dimitri Yordanov: Plasma diagnostics, ELISE operation and modelling
Roman Zagorski: Experimental validation of the fluid solver for SPIDER