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### Description

The upgraded version of the neutral beam injector is described, which provide 1.7 MW power and 15 keV atom energy in injected beam. The nominal extracted proton beam current is 150 A, while the ion source provide the maximal current up to 180 A. The beam duration increased to 30 ms after upgrade in comparison with 8 ms for previous version [1]. The multy-slit 3-grid ion-optical system demonstrate quite good angular divergence about 10 mrad in parallel the slit direction, while the transversal angular divergence is turned out to be ~3 times larger. The beam integral transversal divergence exceeds both calculated value and measured one for single-slit ion optical system. The possible causes are analyzed in the paper. The results of numerical simulation to optimize the ion-optical system on order to minimize the transversal divergence and the results of experimental tests are given.

The eight neutral beams with the total injection power of 14 MW are installed and tested successfully as the injection system for plasma heating in the open magnetic trap.

References

[1] P. Deichuli, V. Davydenko, A. Ivanov, S. Korepanov, V. Mishagin, A. Smirnov, A. Sorokin and N. Stupishin, Rev. Sci. Instrum. 86, 113509 (2015).