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DEVICE

HL-2A TOKAMAK

HL-2A
HL-1M

Nuclear Fusion Reactor & Materials Research

Other experiment devices

In accordance with the national nuclear fusion development program in China, the construction of HL-2A was approved in 1998 by the government as the largest tokamak in China during the period of the Ninth Five-year Plan (1995-2000). The vacuum vessel magnets and supports were based on ASDEX components. The pumping system, energy storage equipment and diagnostics were developed by SWIP.

 

HL-2A was put into operation in 2002. The parameters of HL-2A are summarized in Table 1. The auxiliary heating with a total power of about 10 MW is being developed (as shown in Table 2), of which 3 MW ECRH, 1.5 MW NBI and 1 MW LHCD have already been constructed.

Table 1 HL-2A parameters

Major Radius 1.65m Safety factor 3
Minor Radius 0.4m Volt-second 5Vs
Plasma Current 450kA Plateau of plasma current 5s
Toroidal field 2.8T    
Triangularity δ95 0.3 Number of nulls 2 or 1
Elongation κ95 1.3    

Table 2 Auxiliary heating on HL-2A

Systems Power(MW) Energy/Frequency/Pulse duration
NBI 3 60keV/2s
LHCD 2 2.45GHz/2s
ECRH 5 468GHz/1s/0.55kW
268GHz/1.5s/0.55kW
2140GHz/3s/1MW
8Experiments
HL-2A has an air-core transformer. The programme on HL-2A includes investigation of plasma diagnostics and experimental plasma physics for understanding and improving plasma performance, fusion technology and engineering, and investigation of fusion materials. In 2003 lower single null divertor configuration was achieved. This was the first tokamak discharge with noncircular plasma cross section in China. HL-2A has been equipped with extensive and advanced engineering technologies in recent years. Various fuelling techniques (pellet injection, gas puffing, SMBI), NBI (1.5 MW/45 keV), ECRH (3 MW/68 GHz) and LHCD (1 MW/2.45 GHz) heating systems were improved or installed. The NBI system with four ion sources (power up to 1.5 MW) has been commissioned and operated. More than 30 kinds of diagnostics have been installed, such as HCN interferometer, Thomson scattering, ECE, microwave Doppler reflectometry, CXRS. The plasma parameters have been improved and notable achievements have been made in the last couple of years. For example, the toroidal magnetic field is 2.7 T, the plasma current is 450 kA, the electron and ion temperatures are 5keV and 2.5keV, respectively. Regarding the physics experiments, the toroidal symmetry of the geodesic acoustic mode (GAM) zonal flows has been determined with novel 3-step Langmuir probes for the first time, and the poloidal and radial features of the low frequency (7~9KHz) electric potential and field are simultaneously observed. In addition, the electron fishbone instability under ECRH was studied, and cold supersonic molecule beam injection (SMBI) with clusters was used for fueling and transport study. In Spring 2009, ELMy H-mode discharges were obtained with divertor configuration. It is a milestone in the history of magnetically confined fusion experiment research in China.
8Research program
As the first divertor tokamak in China, broad fundamental studies are involved, such as research on the plasma confinement improvement, divertor, SOL, transport, MHD, energetic particles, plasma facing materials. Relevant engineering and techniques will be improved, such as operation and control, plasma heating, refueling, wall conditioning, diagnostics, modeling. Further topics related to ITER will be explored on HL-2A.
8Next Step
HL-2A modification has been started. It aims at a shaped plasma with more effective and flexible divertor. The detailed design is being made by dedicated group in SWIP. Large support has been received from the government.
The auxiliary heating power of HL-2M, which is the modification of HL-2A, will be up to 20MW. The typical operational parameters are as follows: toroidal field about 2.6T, plasma current about1.2MA, flat-top of plasma about 5s for usual operation and plasma density above 11020m-3. The overall goal of HL-2M is to establish the scientific and technical basis for optimization of the tokamak approach to fusion energy, especially to prepare the important scaling information for the next step machine, ITER.

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