Yuanlai Xie

First plasma of megawatt high current ion source for neutral beam injector of the experimental advanced superconducting tokamak on the test bed.

High current ion source is the key part of the neutral beam injector. In order to develop the project of 4 MW neutral beam injection for the experimental advanced superconducting tokamak (EAST) on schedule, the megawatt high current ion source is prestudied in the Institute of Plasma Physics in China. In this paper, the megawatt high current ion source test bed and the first plasma are presented. The high current discharge of 900 A at 2 s and long pulse discharge of 5 s at 680 A are achieved. The arc discharge characteristic of high current ion source is analyzed primarily.

Design of Neutral Beam-Line of EAST

Neutral beam injector for EAST is designed to deliver deuterium beams with a power of 2 MW to 4 MW at an energy of 50 keV to 80 keV into the plasma with a beam dimension of 12 cm × 48 cm. Considering the beam generation and transmission, a columniform beam-line of Φ 250 cm × 400 cm is designed with a neutralizer, ion dump, calorimeter, bending magnet and cryopanels. The arrangement of the internal elements for the beam-line is reported. A rectangular sleeve coupled to the ion source is employed as the neutralizer. At the downstream of the neutralizer, a dipole magnet separates the residual ions from the beam passage with a reflection radius of 42 cm for the full energy particles. The calorimeter and the ion dump serve as high heat flux components, which will work as thermal inertia targets in the first phase of operation.

The R&D progress of 4 MW EAST-NBI high current ion sourcea)

A high current ion source, which consists of the multi-cusp bucket plasma generator and tetrode accelerator with multi-slot apertures, is developed and tested for the Experimental Advanced Superconducting Tokamak neutral beam injector. Three ion sources are tested on the test bed with arc power of 80 kW, beam voltage of 80 keV, and beam power of 4 MW. The arc regulation technology with Langmuir probes is employed for the long pulse operation of ion source, and the long pulse beam of 50 keV @ 15.5 A @ 100 s and 80 keV @ 52A @ 1s are extracted, respectively.

Overview of Development Status for EAST-NBI System ∗

The neutral beam injection (NBI) system was developed on the Experimental Advanced Superconducting Tokamak (EAST) for plasma heating and current driving. This paper presents the brief history, design, development, and the main experimental results of the RD (2) the design of the EAST-NBI system including the high power ion source, main vacuum chamber, inner components, beam diagnostic system and sub-system; (3) the experimental results of beamline-1 on the summer campaign of EAST in 2014 and, (4) the status of beamline-2 and the future plan of EAST-NBIs.

Development and preliminary results of radio frequency ion source.

A radio frequency (RF) ion source was designed and developed for neutral beam injector. A RF driver test bed was used with a RF generator with maximum power of 25 kW with 1 MHz frequency and a matching box. In order to study the characteristic of RF plasma generation, the capacitance in the matching box was adjusted with different cases. The results show that lower capacitance will better the stability of the plasma with higher RF power. In the future, new RF coils and matching box will be developed for plasma generators with higher RF power of 50 kW.

Calculation of Beam Intensity Distribution for the Neutral Beam Injection in EAST

Theoretical beam intensity distribution is derived for the neutral-beam-injection ion source with a multi-slot extraction in EAST. The beam intensity profile, both along and perpendicular to the injecting direction and the beam power deposition to the inner elements in the neutral beam injector (NBI) are evaluated. The results indicate that the transverse beam intensity is much higher than the longitudinal one. This study could provide information for the design of vacuum system, structure of inner elements and cooling system of the neutral beam injector in EAST.

Performance of positive ion based high power ion source of EAST neutral beam injector

The positive ion based source with a hot cathode based arc chamber and a tetrode accelerator was employed for a neutral beam injector on the experimental advanced superconducting tokamak (EAST). Four ion sources were developed and each ion source has produced 4 MW @ 80 keV hydrogen beam on the test bed. 100 s long pulse operation with modulated beam has also been tested on the test bed. The accelerator was upgraded from circular shaped to diamond shaped in the latest two ion sources. In the latest campaign of EAST experiment, four ion sources injected more than 4 MW deuterium beam with beam energy of 60 keV into EAST.

Thermo-fluid-coupled analysis and simulation of calorimeter of Experimental Advanced Superconducting Tokamak neutral beam injection system on the thermal inertia principle

An efficient and accurate thermo-fluid-coupled analysis is the basis of structure design and optimization for high-heat-flux components in neutral beam injection system of Experimental Advanced Superconducting Tokamak and has an important significance of exploring the optimal structure of components and realizing the temperature control of components at a high-parameter steady-state condition. In this article, take the calorimeter in the Experimental Advanced Superconducting Tokamak–neutral beam injection system on the thermal inertia principle, for example, an accurate numerical solution method of thermo-fluid-coupled analysis based on the turbulent heat transfer is established and combined with the near-wall function model, and the working characteristics of three-dimensional calorimeter plate under different deposited beam powers are simulated and analyzed. The temperature distribution of solid structure and corresponding flow field under given cooling condition is calculated. The results obtained by the proposed method coincide well with experimental results, which validate this method. This study provides a potentially useful method for thermo-fluid-coupled analysis and structural design of other high-heat-flux components in the Experimental Advanced Superconducting Tokamak–neutral beam injection system.

Note: A new regulation method of stable operation of high power cathode ion source

The hot cathode ion source will tend to be unstable when operated with high power and long pulse. In order to achieve stable operation, a new regulation method based on the arc power (discharge power) feedback control was designed and tested on the hot cathode ion source test bed with arc discharge and beam extraction. The results show that the new regulation method can achieve stable arc discharge and beam extraction. It verifies the success of feedback control of arc source with arc power.

Numerical Analysis for the Swirl Tube Structure of the Cooling System in Neutral Beam Injection System

Temperature control of High-Heat-Flux (HHF) components in Neutral Beam Injection (NBI) system is a very important issue for realizing the high-parameters steady state condition of NBI system. As one of the main HHF components, the V-shaped Residual Ion Dump (RID) with cross-sections structure is studied in this article. In order to enhance heat transfer of the fluent, the initial design with the swirl tubes is presented, and one side of the symmetrical ion dump under the designed inlet pressure is modeled. The flow field inside swirl tubes and the temperature distribution of the upper surface of the dump are simulated. This study provides a sample of solving the problem about how to protect all of the HHF components.Copyright