European contributions to the beam source design and R&D of the ITER neutral beam injectors

Abstract

The paper reports on the progress made by the European Home Team in strong interaction with the ITER JCT and JAERI regarding several key aspects of the beam source for the ITER injectors:-integration of the SINGAP accelerator into the ITER injector design. This is a substantially simpler concept than the MAMuG accelerator of the ITER NBI 'reference design', which has potential for significant cost savings, and which avoids some of the weaknesses of the reference design such as the need for intermediate high voltage potentials from the HV power supply and pressurised gas insulation.-high energy negative ion acceleration using a SINGAP accelerator-long pulse (i.e. >1000 s) negative ion source operration in deuterium-RF source development, which could reduce the scheduled maintenance of the ITER injectors (as it uses no filaments), and simplify the transmission line and the auxiliary power supplies for the ion source

Performance of multi-aperture grid extraction systems for an ITER-relevant RF-driven negative hydrogen ion source

“…From the experiences obtained in the last three decades in different experiments worldwide [4][5][6][12][13][14][15][16], the maximum achievable current density under these extreme conditionslow pressure, low extraction voltage, low amount of co-extracted electrons-is in the range of 200-300 A m −2 for deuterium and 300-400 A m −2 for hydrogen (as the amount of co-extracted electrons is much lower in hydrogen, a larger ion current density can be achieved by reducing the filter field strength). These high negative ion current densities could only be achieved until now with caesium seeding of the source.…”

Design optimization of the 100 kV HV bushing for ITER-DNB

“…Electric field distribution and maximum stress values at different regions are indicated in this figure. Additionally, the advantage of this shield is that it can prevent secondary electron generation from the insulator, due to bombardment of primary electrons from cathode and anode side of the screens [9]. Fig.…”

Adaptation of the 1 MV bushing to the SINGAP concept for the ITER NB injector test bed

“…As far as the stress on the insulator surfaces is concerned, extrapolating data in [11], the critical electric field results E c = 16 kV cm −1 (without safety factor) on a pyrex cylinder. In [5], having analysed various experimental data, it is proposed to be 15 kV cm −1 . Therefore, taking into account the RIC related issues, 10 kV cm −1 is proposed to be adopted.…”

“…An alternative design for the ITER NB injector is based on the acceleration to 1 MeV in one single gap, SINGAP [5], which is expected to yield a considerable simplification of the HV components, achieved by suspending the source and the pre-accelerator assembly from the HV bushing.…”