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HL-2A TOKAMAK
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HL-2A is a tokamak based on the original
ASDEX components (vacuum vessel and magnets). The
pumping system, power supply, auxiliary heating, energy
storage equipmemt and diagnostics were constructed by
SWIP. According to the national program to develop nuclear fusion in China, the construction
of HL-2A was approved in 1998 by government as the
largest tokamak in China during the period of National
Ninth Five-years Program
(1995-2000). |
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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 total power of about 10 MW is
being developed (as shown in table 2) |
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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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| DN Triangularity
δ95 |
0.3 |
Number of nulls |
2 or 1 |
| DN Elongation
κ95 |
1.3 |
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8Operation
and Experiments
HL-2A has an air-core transformer. The 3 motor
generators with total energy storage up to 1.3GJ feed the coils
and auxiliary heating systems via power supply (PS). Normally,
the vaccum vessel is baked before an experimental campaign.
Between discharges, siliconization and other wall conditioning
techniques make significant improvement on the plasma
performance and decrease of impurities. The pulsed gas puffing,
in which the timing and amount of gas for each pulse are
precisely controlled, operates as normal fueling. A pellet
injection system which is able to inject up to 8 pellets is
used. The molecular beam injection (MBI), which was first used
on the HL-1M, is routinely employed to investigate the fueling
efficiency of different types of fueling.
More than 30 diagnostics have been installed, such as HCN
interferometer, Thomson scattering and ECE, etc. Some new
diagnostics (MSE and CXRS) are being developed. Modeling and
data acquisition, storage and analyses are progressing steadly.
The first divertor configuration was achieved in 2003
experimental season, and new results on MBI was obtained also.
The past two years (2006-2007) have seen many achievements in
CFS. Experimental database from HL-1M has been integrated into
the ITER confinement database. Initiative research results on
improved plasma confinement and zonal flow were published in
magazines such as Physical Review Letters, Nuclear Fusion, Those
results were also presented on the International Fusion Energy
Conference and granted national patents.
For the HL-2A machine, the operation parameter regime has been
greatly extended, the typical parameters are: totoidal magnetic
field = 2.70T, plasma current = 433kA, plasma discharge duration
= 3.15s, plateau of plasma current = 2.5s, auxiliary heating
power = 2.5MW, average linear density ﹥
6×1019m-3, and the electron temperature up to
4.93keV. For discharge reproducibility, 23 consecutive
discharges (shot: 5450-5472) for lower single null divertor
configuration have been obtained. A number of completely new
results were obtained in 2007 experiment campaign, they are as
follows. 1) Natural particles transport barriers was discovered
for the first times; 2)Quasimode structures was observed which
are in agreement with the theoretic prediction; 3)Toroidal
symmetry for the low frequency zonal flow was conformed |
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Table 2 Auxiliary heating on HL-2A
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Systems |
Power
(MW) |
Pulse
duration(s) |
Energy/
Frequency |
| NBI |
4 |
2 |
60keV |
| LHCD |
3 |
2 |
2.45GHz |
| ICRH |
3 |
2 |
80-100MHz |
| ECRH |
1 |
1 |
66GHz |
8Research
program |
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More than 30 diagnostics have been installed, such as HCN
interferometer, Thomson scattering and ECE, etc. Some new
diagnostics (MSE and CXRS) are being developed. Modeling and data
acquisition, storage and analyses are progressing steadly. The first
divertor configuration was achieved in 2003 experimental season, and
new results on MBI was obtained also. |
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| As the first divertor tokamak in China, broad fundamental
studies are involved in program, such as research on the
plasma confinement improvement, divertor, SOL, transport,
MHD, energetic particles, facing plasma materials, etc.
Relevant engineering and techniques will be improved, such
as operation and control, plasma heating, refueling, wall
conditioning, diagnostics, modeling and others. Further
topics related to ITER will be explored on HL-2A. |
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8Next
Step
HL-2A modification has been started since 2004. It aims at a
medium elongated plasma shape with certain triangularity, and more
effective and flexible divertor. The detailed design is being made by
dedicated group in SWIP. Large support has been gotten from government.
The auxiliary heating power of HL-2M, which is the modification of
HL-2A, will be up to 10MW. The typical operational parameters are as
follows. Toroidal field = 2.57T, plasma current = 1.2MA, plasma duration
= 4s and plasma density 1×1020
m-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 next step machine, ITER.
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