Achievement of ITER-relevant accelerated negative hydrogen ion current densities over 1000 s at the ELISE test facility. (25th June 2019)

• Record Type: Journal Article
• Authors: Wünderlich, D.; Riedl, R.; Bonomo, F.; Mario, I.; Fantz, U.; Heinemann, B.; Kraus, W.
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 59:Number 8(2019:Aug.)
• Publication Date: 2019-06-25
• Subjects: ITER -- neutral beam injection -- negative hydrogen ion source -- RF-driven ion source; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/ab246c
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: The neutral beam heating system for the future international fusion experiment ITER will be based on radiofrequency driven ion sources delivering a large (≈1 × 2 m) and homogeneous negative hydrogen or deuterium ion beam of severals tens of amperes for up to 1 h. Such beams have never been produced before and a dedicated R&D process has been ongoing for more than two decades. An important intermediate step is the size scaling test facility ELISE (Extraction from a Large Ion Source Experiment) with its half-ITER size ion source. Recently, ELISE has fulfilled its first main aim, demonstrating hydrogen ITER-relevant accelerated negative ion current densities over 1000 s, at the required filling pressure of 0.3 Pa, with an electron–ion ratio below one and a beam homogeneity better than 90%. The measures identified as essential for achieving such pulses are the introduction of external permanent magnets and internal potential rods as well as a dedicated caesium conditioning technique.