Speaker
Kihyun Lee
(Department of Engineering)
Description
The combined system of Charge Exchange Spectroscopy (CES) and Beam Emission Spectroscopy (BES) will be developed in Versatile Experimental Spherical Torus(VEST). to measure ion temperature and rotation velocity by not using impurity but fuel hydrogen ion emission line directly. In order to use this system, Diagnostic Neutral Beam Injection (DNBI) system is necessary to supply high energy neutral particles for charge exchange reaction.
A 10kW compact neutral beam injection with high-current ion source using electron gun has been developed for VEST. The target beam current of DNB is ~1A at 10kV to get a sufficient light intensity for CES. The Beam is injected radially toward center stack to obtain all radial diagnostic data for 20ms operation with 4ms time resolution.
The DNBI system consists of four parts: ion source, neutralizer, ion dump with bending magnet and power systems. The electron gun is used in ion source. The ion source can produce high density plasma which is as high as ~ for 20ms by being supplied electrons from electron gun. This value shows that the extractable maximum beam current density is . We used triple electrode system with 2mm gap distance to maximize beam current density at low energy. In order to extract ~1A beam current with 4ms modulation, circular hole with 16mm diameter is chosen as extraction hole. A gas flow neutralizer is used to simply structure. For 90% neutralization efficiency, additional gas is injected to 3mTorr at 50cm neutralization region. Considering turbo pump loads, we installed gas tube surrounding beam path and made gas flows only along the tube. In this paper, detailed design of DNB system is presented. And results of diagnostic by calorimeter are also presented.
Co-authors
Bongki Jung
(Korea Atomic Energy Research Institute, Daejun, South Korea)
Jongyoon Park
(Department of Engineering, Seoul National University, Seoul, South Korea)
Kihyun Lee
(Department of Engineering, Seoul National University, Seoul, South Korea)
Kyungjae Chung
(Department of Engineering, Seoul National University, Seoul, South Korea)
Sungmoo Yang
(Department of Engineering, Seoul National University, Seoul, South Korea)
Yongseok Hwang
(Department of Engineering, Seoul National University, Seoul, South Korea)
YooSung Kim
(Department of Engineering, Seoul National University, Seoul, South Korea)
