Fusion Engineering and Design 56–57 (2001) 685–691 Engineering design of the steady state neutral beam injector for SST-1 S.K. Mattoo *, A.K. Chakraborty, U.K. Baruah, P.K. Jayakumar, M. Bandyopadhyay, N. Bisai, Ch. Chakrapani, M.R. Jana, Raja Onali, V. Prahlad, P.J. Patel, G.B. Patel, B. Prajapati, N.V.M. Rao, S. Rambabu, C. Rotti, S.K. Sharma, S. Shah, V. Sharma, M.J. Singh, N.P. Singh, B. Sridhar Institute for Plasma Research, Bhat, Gandhinagar 382 428, India Abstract The paper presents the complete engineering design of steady neutral beam injector, with emphasis on the deviation in the design from conventional short pulse injectors. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Neutral beam injector; Reionisation loss; Short pulse injectors www.elsevier.com/locate/fusengdes 1. Introduction A single source beam line is expected to deliver 1.7 MW of (1000 S ON/5000 S OFF) neutral beam power at 50 keV H operation and 80 keV D operation [1] with 1 MW of beam power expected in the full energy component. Fig. 1 shows an elevation view of the SST-1 neutral beam injector (NBI) beam line. The long pulse operation (LPO) of the system desires additional design features to be incorporated in the design of the back plate, the neutraliser first stage, filament transformers, magnet and dump arrangement and other compo- nents. Active cooling using Cu–Cr–Zr heat trans- fer elements (HTEs) (allowing low flow rates for large temperature rise in water) has been incorpo- rated in all the components exposed to the heat flux. The power supply system incorporates active power dissipation and the data acquisition and control (DACS) incorporates data compression techniques. This paper discusses the engineering design features of the NBI system with a special emphasis on the features incorporated to account for the LPO ( 1000 S). 2. Injector components 2.1. Ion source In configuration, the ion source is similar to the multipole bucket source used in JET/TEXTOR * Corresponding author. Tel.: +91-2712-69022; fax: +91- 2712-69017. E-mail address: shiban@ipr.res.in (S.K. Mattoo). 0920-3796/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved. PII:S0920-3796(01)00388-X