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HL-2A TOKAMAK
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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. |
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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. |
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Table 1 HL-2A parameters |
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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 |
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| Triangularity
δ95 |
0.3 |
Number of nulls |
2 or 1 |
| Elongation
κ95 |
1.3 |
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Table 2 Auxiliary heating on HL-2A |
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Systems |
Power(MW) |
Energy/Frequency/Pulse duration |
| NBI |
3 |
60keV/2s |
| LHCD |
2 |
2.45GHz/2s |
| ECRH |
5 |
4×68GHz/1s/0.55kW
2×68GHz/1.5s/0.55kW
2×140GHz/3s/1MW |
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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 1×1020m-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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