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The beam extraction was experimentally studied using the prototype whose structure is the same as it is developed at the Budker INP for the beam emission spectroscopy in the TEXTOR tokamak. As result of the test the modulated ion beam 30keV, 0.8A, 0.3s with angular divergence below 1° was obtained. The experimental data with results of the numerical simulations are compared.

A negative-ion-based neutral beam injector system for JT-60U is under construction. The system injects a neutral beam of 10 MW at 500 keV for 10 seconds using one beamline with two large negative ion sources. The total system efficiency of the NBI system is estimated to be 40%. The construction will be completed by the beginning of 1996, following which an NBI current drive and a plasma core heating experiments with a high density plasma will start.

Plasmas of the ASDEX Upgrade tokamak have been heated with H 0 beams of up to 7 MW and D 0 beams of up to 10 MW. Beam modulation allows to inject at any power level between zero and full power. Measurements characterizing the NBI system performance, the power accountability, and the operational experience obtained so far are discussed.

A self consistent physics design for a 50 MW 1 MeV negative-ion based injector has been produced which forms the basis of a preliminary engineering design. Neutronics calculations show that radiation damage to insulators and nuclear heating of cryogenic components does not present any major problem. A detailed report is being issued at NET [1].

For ASDEX-Upgrade additional heating by long pulse neutral injection is foreseen with two injectors, each delivering a power of 6 MW with hydrogen and up to 9 MW with deuterium injection. This paper describes the mechanical design of the injectors and gives an overview of transportation and installation of the first injector in the torus hall.

Neutral Beam Injector (NBI) with negative ion source is under development as one of the most promising heating devices for achieving the objective plasma parameters in the Large Helical Device (LHD) at NIFS. This paper considers the development of high speed cryopumps for the NBI in the LHD. A new type of louvre blind cryopump having parallel 80 K louvre blinds and 3.7K cryopanels, located parallel to the 80 K louvre blinds, is proposed. At the ratios of B/C = 0.92 and D/B = 1.2, the transmission probability of this advanced type is calculated to be 0.72 which means the cryopump system with this louvre blind type can theoretically attain a high pumping speed.

A 600 mm hard-seal gate valve and a fast shutter for the JT-60 Neutral Beam Injector were developed.

Prototype injector unit for JT-60 has been operating since last November. In a present paper we intend to describe the design of power supplies for ion sources and their operating performances. Most of the efforts have been devoted to the system reliability, in particular, control system and grounding system. Transient voltage analysis in case of breakdown was made by numerical calculations and was confirmed by the use of pulse generator in an actual set up.

The operational performance and beam line physics aspects of the first Neutral Beam Injector installed on JET are reported. Injection of more than 8 MW of 80 keV deuterium beams for several seconds into the Tokamak has been successfully achieved.

The neutral beam injection system for JAERI Fusion Torus-2 (JFT-2) was developed and is now in operation. This is one of the largest injection systems in Japan and was de signed, fabricated and tested within about one year. In this paper, the design and test results of power supply system is described.

Prototype neutral beam injector has been constructed aiming at confirming unit performance prior to construction of 14 injector units for JT-60(JAERI Tokamak-60). The unit has cryopumps and cryogenic systems for the cryopumps. Cryopanels are cooled below 3.7 K by the liquid helium. The liquid helium supply system is a completely closed-loop. The capacity of the refrigerator is 300 W at 3.7 K. The cryopumps and the cryogenic systems have been operated successfully since November, 1981. Pumping speed of the cryopumps was measured to be 1.43 × 1061/sec which is close to a design value of 1.37 × 1061/sec.

The neutral beam injector for JAERI Fusion Torus-2(JFT-2) was developed and is now in successful operation. This is one of the largest injection systems in Japan and was designed, fabricated and tested in about one year.

A series of tests has been performed on simulated divertor elements for NET at the JET neutral beam injector test bed. The test section consisted of a water cooled main structure, the surface of which was protected with a carbon based armour in the form of tiles. The scope of these tests was to study the thermal behaviour of mechanically attached tiles with the use of an intermediate soft carbon layer to improve the thermal contact under divertor relevant conditions.

The optimum feed conditions of hydrogen gas into the neutral cell of a Neutral Beam Injector (NBl) are examined using transient simulation analysis of the vacuum system. In the analysis, a neutral cell is directly connected to an ion source without an evacuation port, just as in the usual NBI.s

An overall injector system description is presented first, and this will be followed by a detailed discussion of those problems unique to multiple injector operation on the tokamaks, i.e., power transmission, conditioning, reliability, and failures.

Recent measurements of the production of H- by dissociative attachment of vibrationally excited H2 molecules have indicated that H- current densities of several milliamperes per cm2 are possible in a low density discharge in a magnetic multipole or bucket source. A modified bucket source based on this H- production process is described which is a part of a prototype for a single module of a large-scale neutral beam injector source operating at energies in excess of 100 kV.