Present status and future plans for Tore Supra
Tore Supra is a limiter tokamak with circular plasma cross-section. The superconducting toroidal magnet is a unique feature which allows very long pulse discharges. Tore Supra has ion cyclotron resonance heating and an electron cyclotron system is being installed. Noninductive currents are driven by...
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 2000 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2000
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| Цитувати: | Present status and future plans for Tore Supra / B. Beaumont, A. Becoulet, P. Bibet, C. Darbos, P. Garin, A. Géraud, G. Giruzzi, A. Grosman, G. Martin, M. Ottaviani, Y. Peysson, B. Saoutic, P. Stott, M. Zabiego // Вопросы атомной науки и техники. — 2000. — № 3. — С. 28-32. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860180907990712320 |
|---|---|
| author | Beaumont, B. Becoulet, A. Bibet, P. Darbos, C. Garin, P. Géraud, A. Giruzzi, G. Grosman, A. Martin, G. Ottaviani, M. Peysson, Y. Saoutic, B. Stott, P. Zabiego, M. |
| author_facet | Beaumont, B. Becoulet, A. Bibet, P. Darbos, C. Garin, P. Géraud, A. Giruzzi, G. Grosman, A. Martin, G. Ottaviani, M. Peysson, Y. Saoutic, B. Stott, P. Zabiego, M. |
| citation_txt | Present status and future plans for Tore Supra / B. Beaumont, A. Becoulet, P. Bibet, C. Darbos, P. Garin, A. Géraud, G. Giruzzi, A. Grosman, G. Martin, M. Ottaviani, Y. Peysson, B. Saoutic, P. Stott, M. Zabiego // Вопросы атомной науки и техники. — 2000. — № 3. — С. 28-32. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | Tore Supra is a limiter tokamak with circular plasma cross-section. The superconducting toroidal magnet is a unique feature which allows very long pulse discharges. Tore Supra has ion cyclotron resonance heating and an electron cyclotron system is being installed. Noninductive currents are driven by lower hybrid and by the bootstrap effect. Highlights of previous results include long pulses lasting up to 2 minutes with 280 MJ coupled into the plasma and fully non-inductive discharges lasting up to 75 seconds. 
Tore Supra is presently in the middle of a major shutdown for the installation of a new toroidal pumped limiter. This will be actively cooled with capability for steady state operation at total power levels around 20 MW. Future plans include upgrades to the ion cyclotron heating and lower hybrid current drive systems and a new pellet injector.
|
| first_indexed | 2025-12-07T18:01:54Z |
| format | Article |
| fulltext |
UDC 533.9
28
Problems of Atomic Science and Technology. 2000. N 3. Series: Plasma Physics (5). p. 28-32
PRESENT STATUS AND FUTURE PLANS FOR TORE SUPRA
B.Beaumont, A.Becoulet, P.Bibet, C.Darbos, P.Garin, A.Géraud, G.Giruzzi, A.Grosman,
G.Martin, M.Ottaviani, Y.Peysson, B.Saoutic, P.Stott, M.Zabiego
Association Euratom-CEA, Département de Recherche sur la Fusion, CEA/Cadarache
13108 Saint Paul Lez Durance, France.
ABSTRACT
Tore Supra is a limiter tokamak with circular plasma
cross-section. The superconducting toroidal magnet is a
unique feature which allows very long pulse discharges.
Tore Supra has ion cyclotron resonance heating and an
electron cyclotron system is being installed. Non-
inductive currents are driven by lower hybrid and by the
bootstrap effect. Highlights of previous results include
long pulses lasting up to 2 minutes with 280 MJ coupled
into the plasma and fully non-inductive discharges lasting
up to 75 seconds.
Tore Supra is presently in the middle of a major shutdown
for the installation of a new toroidal pumped limiter. This
will be actively cooled with capability for steady state
operation at total power levels around 20 MW. Future
plans include upgrades to the ion cyclotron heating and
lower hybrid current drive systems and a new pellet
injector.
INTRODUCTION
Tore Supra (Figure 1) has been operated successfully for
12 years since first plasmas were produced in 1988. A
unique feature is the superconducting toroidal magnet,
which permits plasma discharges of long duration. The
plasma has circular cross-section with major radius 2.4 m
and minor radius 0.70 m. The role defined for Tore Supra
within the European Fusion Programme is the integration
of all the various physics and technology aspects that are
required to achieve and investigate high–power, long-
duration plasma discharges.
The initial objective of Tore Supra, set in the 1980s, was
the production of discharges with current of 1.7 MA and
30 s duration at a level of plasma heating of the order of
15 MW. Since then there has been considerable progress
both in fusion technology and in plasma physics.
Moreover the requirements of the next-step experiments
have been identified clearly by the ITER project - in
particular a next-step machine will have discharges of the
order of a thousand seconds. Tore Supra’s power and
particle exhaust and heating and refuelling systems are
being upgraded for 1000 s pulse duration to meet the
requirements of steady state operation.
Figure 1 - overview of Tore Supra.
Experiments carried out in present-day machines have led
to the discovery of new modes of operation (the so-called
advanced tokamak modes) based on controlling the radial
profiles of current density and plasma pressure. They
result in a significant enhancement of the energy
confinement time (by up to a factor 3). A substantial
fraction of the plasma current is self -generated by the
steep pressure gradients. These regimes hold the prospect
of important improvements for a future reactor – in
particular the possibility of maintaining a tokamak in
steady state by a combination of enhanced confinement
and a high fraction of bootstrap current.
SUMMARY OF PLASMA PERFORMANCE
Tore Supra’s experimental programme has been focussed
on the study of long duration plasmas with non-inductive
currents. Long pulse discharges lasting up to 2 minutes
were produced by coupling about 2.5 MW of lower
hybrid power into plasmas with relatively low current,
Ip ~ 0.8 MA, and low density <n> ~ 1.5x1019 m-3. An
example is shown in Figure 2. The total energy coupled
29
Problems of Atomic Science and Technology. 2000. N 3. Series: Plasma Physics (5). p. 28-32
into one of these discharges – more than 280 MJ – is a
world record.
2.0
1.0
q o
8
6
4
2
keV T eo
T e (r/a0.4)
0.20
0.10
0
120100806040200
Time (s)
W e-RLW (MJ)
W e (MJ)
3.0
2.5
2.0
1.5
1.0
0.5
0
V l (V)
P lh (MW)
I p (MA)
l i
15
0
Flux (Wb)
3.0
2.0
1.0
0
n eo (10
19
m
-3
)
Z eff
Figure 2 - time traces of the 2 minute plasma.
Plh - LH power, li - internal inductance, Ip - plasma
current, Vl - loop voltage, Zeff - plasma effective charge,
ne0 - central electron density, q0 - central q value, Te0 -
central electron temperature, Te(r/a = 0.4) - electron
temperature at radius r/a = 0.4, We - electron stored
energy, WeRLW - Rebut Lallia Watkins prediction.
Lower hybrid current drive has been used also to produce
discharges with zero loop voltage lasting up to 75 s. This
type of plasma exhibits a stationary, globally-enhanced
electron confinement – the so-called lower hybrid
enhanced performance (LHEP) as well as a stationary
transport barrier on the electron temperature. Similar
enhancement was observed during the final 60 s of the 2
minute discharge.
Higher coupled powers have been maintained for shorter
periods. A maximum of 5.3 MW has been coupled for 6 s
with two lower hybrid launchers and 10 MW for 2 s has
been coupled with three ion cyclotron antennas.
POWER & PARTICLE EXHAUST
One of the crucial problems for tokamak operation with
long-duration, high performance plasmas is the exhaust of
power and particles. At start-up in 1988, Tore Supra was
equipped with a first generation of actively cooled plasma
facing components. It was found that the power handling
capacity was limited to about 3 MW for long pulse
operation. This is too low to study the steady-state plasma
regimes relevant to the problems posed by next step
machines. This limitation is being addressed as the first
stage of a series of upgrades. This is known as CIEL - a
French acronym for Composants Internes et Limiteur.
The main items (see Figure 3) are a toroidal pumped
limiter, improved wall protection and upgraded cooling
for in-vessel components. Tore Supra is presently closed
for the installation. Operation with part of the new limiter
will start in 2001 and with the full limiter in 2002.
Figure 3 – schematic of the CIEL upgrade showing the
toroidal pumped limiter and wall protection panels.
The toroidal pumped limiter is designed to remove about
15 MW under steady state conditions. The flat limiter
with a total area of 7.5 m2 is located at the bottom of the
torus. The limiter is assembled out of many separate
radial elements called “fingers”. The plasma-facing
surface of each finger (Figure 4) is covered with carbon
fibre composite (CFC) tiles. The CFC tiles are attached to
a water-cooled hard copper (CuCrZr) heat sink via an
intermediate layer of ductile high purity copper. This
technology allows the pumped limiter to handle local
power fluxes up to 10 MW m2. The fingers are mounted
on a carefully aligned support structure that is isolated
mechanically from the vacuum vessel.
30
Problems of Atomic Science and Technology. 2000. N 3. Series: Plasma Physics (5). p. 28-32
Figure 4 - schematic of a limiter finger.
The CIEL upgrade includes the installation of poloidal
bumpers to protect the walls and heating antennas against
runaway electrons and disruptions. Actively cooled
protection panels are being installed on the walls to
handle radiated power loads of about 1 MW m-2. Thus
equipped, Tore Supra will be able to handle steady state
powers in excess of 20 MW, with about 15 MW removed
via the limiter and the remainder radiated to the walls.
Measuring their surface temperature using a set of
infrared endoscopes will protect the toroidal pumped
limiter and other internal components. These instruments
will be located in six vertical ports equally spaced around
the torus.
Particle control in CIEL will be achieved by means of
particle exhaust regions (neutralisers) situated under the
limiter and linked to a pumping system outside the torus.
Cryo-mechanical pumps with the capacity to exhaust the
entire plasma particle content in one second have been
developed to match the required fluxes.
HEATING AND REFUELING
Tore Supra presently has lower hybrid and ion cyclotron
systems that were designed for 30 s pulse operation. An
electron cyclotron heating and current drive system is
being installed already and will be fully operational in
2003. This will operate at 118 GHz with six gyrotrons
coupled into the plasma through a 6-channel antenna and
steerable mirrors. The coupled power will be in the range
of 2 to 3 MW with a nominal pulse length of 210 s.
The next step in the enhancement programme will be the
upgrade of systems for plasma heating and refuelling in
order to make them compatible with operation at about
20 MW for discharges lasting for about 1000 s.
Due to budgetary limitations, the CIMES (an acronym for
Composants pour l'Injection de Matière et d'Energie en
Stationnaire) project is being planned in three phases. The
first phase is presently at the approval stage and is
planned for completion in 2005. This will upgrade the
lower hybrid system to 8 MW of steady state coupled
power. A new pellet injector is also part of the first phase.
The second phase, if approved, will start in 2002 and be
completed in 2008. This will upgrade the ion cyclotron
system to 9 MW steady state coupled power. The third
phase will not be decided until 2005 and a choice will be
made between a number of options. These include a
further 4 MW of lower hybrid, a further 3 MW of ion
cyclotron, more electron cyclotron heating or a new
ergodic divertor.
Lower Hybrid System
The lower hybrid system operates at 3.7 GHz with two
launchers. One launcher is of the original design and is
not suitable for steady state operation at high power. A
new launcher was installed and tested in 1999. It is of a
new design, shown in Figure 5, with the capacity to
couple 4 MW steady state. The antenna surface and
number of waveguides of the new design is roughly twice
that of the older version and can couple twice as much
power when operated at the same power density. A
second launcher of the new design will be installed to
bring the total coupled power capability to 8 MW.
Figure 5 - second generation lower hybrid launcher
showing poloidal bumper protection.
31
Problems of Atomic Science and Technology. 2000. N 3. Series: Plasma Physics (5). p. 28-32
Extra generator power is required to routinely couple
4 MW per launcher. About 5.6 MW per launcher is
required at the generator to allow for transmission loses,
reflected power and to give a margin for operational
flexibility. The existing 500 kW klystrons (two banks
each of eight tubes) will be upgraded with new klystrons
rated at 700 kW steady state.
Ion Cyclotron System
The upgrade of the Ion Cyclotron system will form the
second phase of the CIMES upgrade. The steady-state
capability of the existing ion cyclotron system is limited
both by the antennas (Figure 6) and the generators.
It is proposed to build three new antennas which will be
completely actively cooled, allowing 4 MW to be coupled
into the plasma routinely in steady state from each
antenna – a potential total of 12 MW. However, as
discussed below, this will be limited initially to 9 MW by
the generator capacity. The antennas will be based on the
same principles as the antennas foreseen for ITER-FEAT.
Some component development, in particular of the
matching capacitors, is required.
Figure 6 - ion cyclotron antenna.
The generators will be upgraded for steady state operation
by replacing the tetrodes in the final amplification stage
with diacrodes. The first two stages of amplification also
will be improved in order to make them compatible with
steady-state operation. The diacrodes presently available
are rated at 2 MW. Each antenna is driven by two
diacrodes. Allowing for coupling losses and an operating
margin, this will be sufficient to couple 3 MW per
antenna – a total of 9 MW with three antennas. However
the generators will be compatible with using a 3 MW
diacrode and, if this becomes available, the coupled
power could be increased to 12 MW.
Fuel injection system
It is planned to buy a single-stage pneumatic injector,
equipped with a screw extruder, from the PELIN
company (associated with the Technical State University
of Saint Petersburg). This has the necessary reliability and
performance to refuel Tore Supra for 1000 s pulses. It will
be installed with provision for high-field-side injection.
FUTURE PROGRAMME
Tore Supra’s future programme will exploit these new
enhancements to the power and particle exhaust and
heating and refuelling systems. The programme is
directed at steady state discharges with total coupled
energy of 20 GJ. Intermediate steps include targets of
1 GJ in 2003, 2 GJ in 2004 and 10 GJ in 2005. The key
factor that sets the time-scale is the progressive increase
in the available heating power. Figure 7 shows the steady
state heating power planned for phases I and II as well as
the interim capability for shorter (30 s) pulses.
0
2
4
6
8
10
12
14
16
18
20
2000 2001 2002 2003 2004 2005 2006 2007 2008
Year
C
o
u
p
le
d
p
o
w
er
(
M
W
)
Figure 7 - Planned coupled power capability in phases I &
II; steady state (triangles) and 30 s pulse (squares).
The first phase of the heating upgrade, when completed in
2005, will make available 8 MW of steady state coupled
lower hybrid power. Combined with the existing ion and
electron cyclotron heating, this will give a total of 12 MW
steady state or 19 MW for a 30 s pulse. When phase II is
completed in 2008, a total of 19 MW will be available
32
Problems of Atomic Science and Technology. 2000. N 3. Series: Plasma Physics (5). p. 28-32
steady state. The operating range in current and density
for a fully non-inductive current corresponding to these
coupled powers is shown in Figure 8.
Adding a further 4 MW of lower hybrid (one option for
phase III) would extend the operating space to higher
density. Increasing the ion cyclotron or electron cyclotron
heating would improve profile control. A decision on
these options can be taken in the light of experience with
phase I.
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
I p
(
M
A
)
6543210
<n> (10
19
m
-3
)
D
en
si
ty
to
o
lo
w
f
or
go
od
I
C
c
ou
pl
in
g
qedge < 3
Greenwald
limit
Vloop > 0
Vloop < 0
Figure 8 - Limits of current and density for fully non-
inductive currents. The solid line indicates 12 MW total
coupled power (8 MW LH + 2 MW IC + 2 MW EC)
coresponding to the steady state capability in 2005. The
broken line indicates 19 MW total coupled power
(8 MW LH + 9 MW IC + 2 MW EC) corresponding to the
30 s pulse capability in 2005 and steady state in 2008.
Two broad categories of experimental regime are
foreseen, roughly corresponding to the limits of the
permitted operating range in current and density. Typical
parameters are indicated in Table 1.
At the low density, high current limit (typically ~
1.5x1019 m-3 and 1.4 MA), the steady state capability will
be exploited primarily for testing technology components.
It is important for next step experiments to show that
systems for plasma heating, refuelling, power and particle
exhaust can be operated reliably under steady state
conditions. In phase I this will be at 12 MW total power;
with phase II it will increase to 19 MW.
A higher density, lower current regime (typically about
3.8x1019 m-3 and 0.8 MA) with lower hybrid current drive
and both ion and electron cyclotron heating is better
suited to the exploration of advanced confinement modes.
With phase I, this regime will be accessible for 30 s
pulses; with phase II, it can be sustained for 1000 s. An
important objective is to show that the advanced
confinement modes can be extrapolated to and maintained
under steady-state conditions. The programmes on JET
and Tore Supra complement each other in this respect.
JET can study these modes in deuterium-tritium plasmas
and Tore Supra will have the capacity to maintain them
for time scales longer than the characteristic times for the
evolution of the current profiles.
Table 1 - typical operating regimes.
Objective Technology Adv. Tokamak
Phase I 2005 12 MW 1000 s 19 MW 30 s
Phase II 2008 19 MW 1000 s 19 MW 1000 s
Density ~ 1.5x1019 m-3 ~ 3.8x1019 m-3
Current at 4 T 1.4 MA 0.8 MA
Edge q ~ 3 ~ 5.5
Bootstrap fraction ~ 20% ~ 50%
Profile control Not required Essential
H factor H ~ 1 H ~ 2
SUMMARY
An overview of Tore Supra’s present status and future
plans has been given. New toroidal pumped limiter and
wall protections are presently being installed. Major
upgrades are planned for the heating and refuelling
systems to give tore Supra the capability to operate at
high power levels under steady state conditions. This will
have important applications for the physics and
technology of next-step tokamaks.
|
| id | nasplib_isofts_kiev_ua-123456789-82362 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T18:01:54Z |
| publishDate | 2000 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Beaumont, B. Becoulet, A. Bibet, P. Darbos, C. Garin, P. Géraud, A. Giruzzi, G. Grosman, A. Martin, G. Ottaviani, M. Peysson, Y. Saoutic, B. Stott, P. Zabiego, M. 2015-05-28T19:53:20Z 2015-05-28T19:53:20Z 2000 Present status and future plans for Tore Supra / B. Beaumont, A. Becoulet, P. Bibet, C. Darbos, P. Garin, A. Géraud, G. Giruzzi, A. Grosman, G. Martin, M. Ottaviani, Y. Peysson, B. Saoutic, P. Stott, M. Zabiego // Вопросы атомной науки и техники. — 2000. — № 3. — С. 28-32. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/82362 533.9 Tore Supra is a limiter tokamak with circular plasma cross-section. The superconducting toroidal magnet is a unique feature which allows very long pulse discharges. Tore Supra has ion cyclotron resonance heating and an electron cyclotron system is being installed. Noninductive currents are driven by lower hybrid and by the bootstrap effect. Highlights of previous results include long pulses lasting up to 2 minutes with 280 MJ coupled into the plasma and fully non-inductive discharges lasting up to 75 seconds. 
 Tore Supra is presently in the middle of a major shutdown for the installation of a new toroidal pumped limiter. This will be actively cooled with capability for steady state operation at total power levels around 20 MW. Future plans include upgrades to the ion cyclotron heating and lower hybrid current drive systems and a new pellet injector. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Magnetic confinement Present status and future plans for Tore Supra Article published earlier |
| spellingShingle | Present status and future plans for Tore Supra Beaumont, B. Becoulet, A. Bibet, P. Darbos, C. Garin, P. Géraud, A. Giruzzi, G. Grosman, A. Martin, G. Ottaviani, M. Peysson, Y. Saoutic, B. Stott, P. Zabiego, M. Magnetic confinement |
| title | Present status and future plans for Tore Supra |
| title_full | Present status and future plans for Tore Supra |
| title_fullStr | Present status and future plans for Tore Supra |
| title_full_unstemmed | Present status and future plans for Tore Supra |
| title_short | Present status and future plans for Tore Supra |
| title_sort | present status and future plans for tore supra |
| topic | Magnetic confinement |
| topic_facet | Magnetic confinement |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/82362 |
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