ICRF plasmas for fusion reactor applications
The ICRF plasma production technique is considered as a promising alternative tool for the following applications in the present and next generation superconducting fusion devices: (i) Wall conditioning in the presence of permanent high magnetic field; (ii) Assistance for the tokamak start-up at low...
Збережено в:
| Опубліковано в: : | Вопросы атомной науки и техники |
|---|---|
| Дата: | 2007 |
| Автори: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
| Формат: | Стаття |
| Мова: | Англійська |
| Опубліковано: |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2007
|
| Теми: | |
| Онлайн доступ: | https://nasplib.isofts.kiev.ua/handle/123456789/110347 |
| Теги: |
Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | ICRF plasmas for fusion reactor applications / A. Lyssoivan, R. Koch, D. Van Eester, M. Van Schoor, G. Van Wassenhove, M. Vervier, R. Weynants, J. Buermans, T. Matthys, H.G. Esser, O. Marchuk, O. Neubauer, V. Philipps, G. Sergienko, V. Bobkov, H.-U. Fahrbach, D.A. Hartmann, A. Herrmann, J.-M. Noterdaeme, V. Rohde, B. Beaumont, E. Gauthier, G.P. Glazunov, A.V. Lozin, V.E. Moiseenko, N.I. Nazarov, O.M. Shvets, K.N. Stepanov, E.D. Volkov, I.L. Beigman, L.A. Vainshtein // Вопросы атомной науки и техники. — 2007. — № 1. — С. 30-34. — Бібліогр.: 27 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859593194500521984 |
|---|---|
| author | Lyssoivan, A. Koch, R. Van Eester, D. Van Schoor, M. Van Wassenhove, G. Vervier, M. Weynants, R. Buermans, J. Matthys, T. Esser, H.G. Marchuk, O. Neubauer, O. Philipps, V. Sergienko, G. Bobkov, V. Fahrbach, H.-U. Hartmann, D.A. Herrmann, A. Noterdaeme, J.-M. Rohde, V. Beaumont, B. Gauthier, E. Glazunov, G.P. Lozin, A.V. Moiseenko, V.E. Nazarov, N.I. Shvets, O.M. Stepanov, K.N. Volkov, E.D. Beigman, I.L. Vainshtein, L.A. |
| author_facet | Lyssoivan, A. Koch, R. Van Eester, D. Van Schoor, M. Van Wassenhove, G. Vervier, M. Weynants, R. Buermans, J. Matthys, T. Esser, H.G. Marchuk, O. Neubauer, O. Philipps, V. Sergienko, G. Bobkov, V. Fahrbach, H.-U. Hartmann, D.A. Herrmann, A. Noterdaeme, J.-M. Rohde, V. Beaumont, B. Gauthier, E. Glazunov, G.P. Lozin, A.V. Moiseenko, V.E. Nazarov, N.I. Shvets, O.M. Stepanov, K.N. Volkov, E.D. Beigman, I.L. Vainshtein, L.A. |
| citation_txt | ICRF plasmas for fusion reactor applications / A. Lyssoivan, R. Koch, D. Van Eester, M. Van Schoor, G. Van Wassenhove, M. Vervier, R. Weynants, J. Buermans, T. Matthys, H.G. Esser, O. Marchuk, O. Neubauer, V. Philipps, G. Sergienko, V. Bobkov, H.-U. Fahrbach, D.A. Hartmann, A. Herrmann, J.-M. Noterdaeme, V. Rohde, B. Beaumont, E. Gauthier, G.P. Glazunov, A.V. Lozin, V.E. Moiseenko, N.I. Nazarov, O.M. Shvets, K.N. Stepanov, E.D. Volkov, I.L. Beigman, L.A. Vainshtein // Вопросы атомной науки и техники. — 2007. — № 1. — С. 30-34. — Бібліогр.: 27 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | The ICRF plasma production technique is considered as a promising alternative tool for the following applications in the present and next generation superconducting fusion devices: (i) Wall conditioning in the presence of permanent high magnetic field; (ii) Assistance for the tokamak start-up at low inductive electric field (E₀ ~ 0.3 V/m in ITER); (iii) Target dense plasma production (ne ≥ 10¹⁹ m⁻³) in stellarators. The paper presents a review of the ICRF plasma production technique and its applications in the present-day tokamaks and stellarators. The perspective of the alternative technique applications in ITER is analyzed in the frame of 0-D plasma modeling.
ВЧ-метод утворення плазми (ICRF) розглядається як перспективний альтернативний інструмент для таких застосувань у сучасних й майбутніх надпровідних термоядерних установках: (i) ВЧ-чистка стінок в присутності постійного сильного магнітного поля; (ii) Aсистування старту токамака у режимі слабого вихрового електричного поля (E₀~ 0.3 В/м в ITERі); (iii) Створення густої вихідної плазми (ne ≥ 10¹⁹ м⁻³) в стелараторах. Зроблено огляд ВЧ-метода створення плазми та його застосування у сучасних токамаках й стелараторах. В рамках моделювання 0-D плазмовим кодом проведено аналіз перспективності використання даного метода в ITERі.
ВЧ-метод создания плазмы (ICRF) рассматривается как перспективный альтернативный инструмент для следующих применений в современных и будущих сверхпроводящих термоядерных установках: (i) ВЧ-чистка стенок в присутствии постоянного сильного магнитного поля; (ii) Aссистирование старту токамака в режиме слабого вихревого электрического поля (E₀ ~ 0.3 В/м в ITERе); (iii) Создание плотной исходной плазмы (ne ≥ 10¹⁹ м⁻³) в стеллараторах. Сделан обзор ВЧ-метода создания плазмы и его применений в современных токамаках и стеллараторах. В рамках моделирования 0-D плазменным кодом проведен анализ перспективности использования данного метода в ITERе.
|
| first_indexed | 2025-11-27T18:32:46Z |
| format | Article |
| fulltext |
ITER AND FUSION REACTOR ASPECTS
*Partners in the Trilateral Euregio Cluster (TEC)
30 Problems of Atomic Science and Technology. 2007, 1. Series: Plasma Physics (13), p. 30-34
ICRF PLASMAS FOR FUSION REACTOR APPLICATIONS
A. Lyssoivan1, R. Koch1, D. Van Eester1, M. Van Schoor1, G. Van Wassenhove1, M. Vervier1,
R. Weynants1, J. Buermans2, T. Matthys2, H.G. Esser3, O. Marchuk3, O. Neubauer3, V. Philipps3,
G. Sergienko3, V. Bobkov4, H.-U. Fahrbach4, D.A. Hartmann4, A. Herrmann4, J.-M. Noterdaeme4,5,
V. Rohde4, B. Beaumont6, E. Gauthier6, G.P. Glazunov7, A.V. Lozin7, V.E. Moiseenko7,
N.I. Nazarov7†, O.M. Shvets7, K.N. Stepanov7, E.D. Volkov7, I.L. Beigman8, L.A. Vainshtein8,
TEXTOR Team, ASDEX Upgrade Team, TORE SUPRA Team and U-3M Team
1 LPP-ERM/KMS, Association EURATOM-BELGIAN STATE, 1000 Brussels, Belgium*;
2 Royal Military Academy, ERM/KMS, 1000 Brussels, Belgium;
3 Institut für Plasmaphysik FZ Jülich, EURATOM Association, D-52425 Jülich, Germany*;
4 Max-Planck Institut für Plasmaphysik, EURATOM Association, D-85748 Garching, Germany;
5 Gent University, EESA Department, B-9000 Gent, Belgium;
6 Association EURATOM-CEA, CEA Cadarache, 13108 St Paul lez Durance, France;
7 Institute of Plasma Physics, NSC KIPT, 61108 Kharkov, Ukraine;
8 P.N.Lebedev Physical Institute of Russian Academy of Sciencies, 119991 Moscow, Russia
The ICRF plasma production technique is considered as a promising alternative tool for the following applications in
the present and next generation superconducting fusion devices: (i) Wall conditioning in the presence of permanent
high magnetic field; (ii) Assistance for the tokamak start-up at low inductive electric field (E0 ~ 0.3 V/m in ITER);
(iii) Target dense plasma production (ne ≥1019 m-3) in stellarators. The paper presents a review of the ICRF plasma
production technique and its applications in the present-day tokamaks and stellarators. The perspective of the alternative
technique applications in ITER is analyzed in the frame of 0-D plasma modeling.
PACS: 52.25.Jm, 52.35.Hr, 52.40.Fd, 52.40.Hf, 52.50.Qt
1. INTRODUCTION
The plasma production technique based on absorption
of the radio-frequency power in the Ion Cyclotron Range
of Frequencies (ICRF) is becoming an indispensable tool
for present and next generation superconducting fusion
devices because of its high potential for solving several
basic problems of reactor oriented machines:
• Wall conditioning (tritium retention, surface isotope
exchange, wall cleaning/coating) with ICRF plasmas in
the presence of permanent high magnetic field in
stellarators [1,2] and tokamaks [3].
• Assistance with the ICRF pre-ionization for the tokamak
start-up at low inductive electric field (E0≈ 0.3 V/m in
ITER) [4].
• Target dense RF plasma production (ne ≥1019 m-3) in the
stellarators [5,6].
The paper presents a review of the alternative ICRF
plasma production technique developed earlier for routine
use in the stellarators [5] and successfully adapted later
for the tokamak applications. The concept of the ICRF
plasma production based on absorption of the RF power
mainly by the electrons via collisions is described. The
main plasma parameters achieved in different scenarios
are characterized and compared with those predicted by
newly developed 0-D Plasma code [7]. The crucial effect
of the RF power deposition to the electrons in the plasma
core on build-up of the target dense (~1019 m-3) plasmas
in stellarators and on performance of more homogeneous
conditioning plasmas (<1018 m-3) in large-size divertor
tokamaks was predicted numerically and successfully
demonstrated in the experiments [8,9]. The main results
on ICRF discharge conditioning (ICRF-DC) achieved in
the present fusion machines in the gas mixtures of
(He+H2), (D2+H2), (He+O2), and (H2+N2) are analyzed in
terms of the gas species removal rate. The results on
ICRF assisted tokamak start-up (TEXTOR) are presented
and compared with the non-assisted start-up. The antenna
ability to produce target dense plasma in stellarator
(U-3M) is analyzed in terms of the plasma production
rate.
Finally, we discuss a perspective on the feasible
applications of the new technique in ITER for wall
conditioning in between shots and for tokamak start-up
assistance.
2. BASIC PRINCIPLES OF ICRF PLASMA
PRODUCTION
The initiation of ICRF discharge in a toroidal
magnetic field BT results from the absorption of RF
energy mainly by electrons [10,11]. The RF zE~ -field
(parallel to the BT-field) is considered to be responsible
for this process. However, the electromagnetic waves in
the typical ICRF band (~10−100 MHz) cannot propagate
in vacuum in the present-size fusion devices [12].
Therefore, the neutral gas breakdown and initial
ionization may only occur locally at the antenna-near zE~ -
field (evanescent in vacuum). Analytical study and 3D
simulations show that, in general case, ICRF antenna can
generate the RF zE~ -field in vacuum inductively and/or
electrostatically [11]. Further analysis of the parallel
equation of motion of the electrons revealed that the
neutral gas breakdown and initial ionization will be
efficient when the electrons will be trapped in the antenna
RF potential wells for many periods and the amplitude of
the antenna electric field will meet the boundary condition
[10]:
eLmrE~me zezie /0.2)())(2 /( 21/2 ωεω ≤≤ . (1)
Here )( dzE~dE~2L zzz = is the parallel length scale of
the ponderomotive potential.
As soon as the electron plasma frequency ωpe becomes
of the order of ω (it occurs at a very low density
~1012−1014 m-3 in the frequency range 10−100 MHz),
plasma waves can start propagating in a relay-race regime
governed by the antenna κz-spectrum, causing further
31
space ionization of the neutral gas and plasma build-up in
the torus. Because of the very low plasma temperature
during the ionization phase (Te~2−5 eV [3,11]), the RF
power is expected to be dissipated mostly collisionally
either directly or through conversion to ion Bernstein
waves (IBW) if ciωω > or by conversion at the Alfvén
resonance (AR) if ciωω < . Such a non-resonant coupling
allows RF plasma production at any BT.
3. ICRF PLASMA CHARACTERIZATION
3.1. NEUTRAL GAS BREAKDOWN
On applying RF voltage/power at the antenna straps,
the neutral gas breakdown occurs after some time-delay
characterized by the breakdown time tbd [9].
Data for the neutral gas breakdown time obtained
from the RF discharges with similar RF power per strap
(30−50 kW) and frequency (~30 MHz) were found in a
good agreement for three European tokamaks TEXTOR,
JET and AUG in the measured gas pressure range (Fig.1).
Fig.1. Pressure dependence of the RF breakdown time as
derived from the Hα emission analysis
(PRF/Ant.strap≈30−50 kW, f≈30 MHz, ω=4ωcHe+=2ωcD=ωcH)
and compared with 0-D modeling
Further analysis of the neutral gas breakdown phase
was performed with a recently developed 0-D Plasma code
[7], which solved numerically a set of differential particle
and energy balance equations for the atoms, electrons and
ions. The following atomic reactions with the updated
reaction rates have been considered: electron collisional
excitation and ionization of the atoms, radiative,
dielectronic and three-body recombination and charge-
exchange recombination. The predicted gas breakdown
time, tbd, derived from the balance of the power losses
between the electron impact ionization and the electron-ion
Coulomb collisions was found in an agreement with the
experimental data (Fig.1). It might be an indication that:
• Collisional ionization by the electrons is the principal
mechanism of gas ionization in the ICRF band;
• For the fixed RF power density (antenna zE~ -field), the
breakdown time is independent on the machine size;
• Plasma waves contribute to the gas ionization in torus
starting from the breakdown phase, at which the
condition ωpe > ω is already fulfilled.
3.2. ICRF PLASMA BUILD-UP
The plasma production process has been studied on
TEXTOR under various conditions as summarized in
Fig.2. Helium ICRF plasmas with central line averaged
density (ne0 5×1016−3×1018 m-3) were reliably produced
in a wide range of the toroidal magnetic field
BT 0.20−2.24 T (2ωci ω 20ωci) and gas pressure
(~10-3−10-1 Pa) without changing the RF generator
frequency (f=32.5 MHz). The RF plasma density was
proportional to the injected RF power (a sign of weakly
ionized plasma) and increased with the torus pressure.
The ionization degree roughly estimated from the
averaged density/pressure measurements was found to be
rather low, γi=ne/(ne+n0)<0.1.
Fig.2. BT-dependence of the central line-averaged density
of the He-plasmas (symbols) and the coupling efficiency
of the A1-antenna (solid line) at different gas pressure,
RF power and antenna phasing
Analysis of the exterior Dα line-integrated emission
measured in different sections of the torus vessel showed
that the distribution of ICRF plasmas in the toroidal
direction was uniform. The electron temperature (deduced
from the spectroscopic and electric probe measurements)
varied in the range 3-30 eV, increasing in the low gas
pressure case [11] or in the presence of FW-IBW mode
conversion [9]. For the latter case, 1-D RF code [13]
predicts an enlargement of the RF power fraction
absorbed by the electrons from 34 to 64 % on increasing
the H+-concentration in the (He+H2)-plasmas from 2 to
10% [14]. The promising mode conversion scenario
performed at two different frequencies (30 and 36.5 MHz)
was used later during the ICRF wall conditioning
experiments in ASDEX Upgrade (AUG) for further
plasma extension towards HFS (Fig.3).
Fig.3. The CCD top view of ICRF plasmas produced in
AUG at f=30 MHz (a) and at f=36.5 MHz (b) under the
similar other conditions: PRF-pl≈50 kW, BT=2.4 T, gas
mixture H2/(He+ H2)~0.1-0.3, p≈4×10-2 Pa
3.3. ANTENNA-PLASMA LOADING
The antenna-plasma coupling efficiency is defined as a
fraction of generator power coupled by the plasma,
η=PRF-pl /PRF-G [9]. For the standard ICRH antenna, this
factor becomes rather low (η0 20−40%) in the regime of
low-density (ne~1017 m-3) helium ICRF plasma in contrast
to the heating scenarios applied for target dense plasmas
(η≥90% at ne>1019 m-3). Such difference is caused by the
antenna polarization. The standard antenna is optimized to
couple the RF power efficiently to fast wave (FW), which
propagates usually in the high-density plasmas only. To
achieve an improved coupling efficiency η1 of the
standard ICRF antenna during low-density RF plasma
production, several recipes have been found and
successfully tested:
0
20
40
60
80
100
120
0-D Model
10-3 10-2 10-1
Gas pressure [Pa]
Br
ea
kd
ow
n
Ti
m
e
[
m
s]
JET
AUG
TEXTOR
η1
11
10
n
[c
m
]
e0
_
-3
12
10
0.1
0.5
1.0
η
1
[r.
u.
]
0.0 0.5 1.0 1.5 2.0 2.5
B [ T ]T
Prf1=300 kW, Prf2=200 kW, A1=0, p=1.5x10**-1 Pa
Prf1=300 kW, Prf2=300 kW, A1=180, p=8x10**-3 Pa
Prf1=250 kW, Prf2=0 kW, A1=180, p=1.5x10**-1 Pa
Prf1=500 kW, Prf2=500 kW, A1=0, p=5x10**-3 Pa
Prf1=200 kW, Prf2=200 kW, A1=180, p=5x10**-3 Pa
Prf1=200 kW, Prf2=200 kW, A1=0, p=8.0x10**-3 Pa
(a) (b)
32
• Lower BT or higher frequency operation
(η1/η0 1.6−2.0) [11,15];
• ECRF pre-ionization/assistance for the ICRF plasma
production (η1/η0 1.4) [16];
• Mode conversion in plasmas with two ion species
(η1/η0 2.0−3.0) [15];
• Antenna “magnetic tilting” towards Btot=BT+BV by
superposing an additional vertical magnetic field
BV<<BT (η1/η0 1.2) [17].
3.4. GENERATION OF HIGH-ENERGY
H AND D ATOMS
All ICRF-DC experiments performed until now
reported on the generation of high-energetic fluxes of H
(with energies up to 60 keV) and of D atoms (up to
25 keV) detected by a neutral particle analyzer in
deuterium or helium RF plasmas [3]. Detailed study of the
phenomenon revealed that ion cyclotron absorption
mechanism plays a fundamental role in the generation of
the high-energy H and D atoms:
• Intensity of the locally collected flux of CX neutrals
strongly correlated with the position of the
ω=ωcH=2ωcD layer in the plasma cross-section [11];
• Heating at the first cyclotron harmonic (ω=2ωci)
creates tail in the H-atom spectra at higher energy than
fundamental heating, in line with the fast particle
distributions caused by RF quasilinear diffusion [18].
10
9
8
7
6
5
4
3
10
9
8
7
6
5
4
3
lo
g1
0
(fl
ux
/e
V
s
te
r c
m
s)
2
lo
g1
0
(fl
ux
/e
V
s
te
r c
m
s)
2
0.0 5.0 10.0
E [keV]
<T >=1.2 keVH
<T >=0.8 keVD
<T >=2.6 keVH
<T >=0.3 keVD
(a)
(b)
AUG #19480
AUG #19480
Fig.4. Hydrogen (a) and Deuterium (b) atom spectra
observed with NPA in He-plasmas (squares) and in
(He+H2)-plasmas (circles) (PRF ≈60 kW, f=30 MHz,
p≈ 4.0×10-2 Pa, BT=2.4 T)
Figure 4 shows typical H and D atoms spectra observed in
the AUG ICRF discharge in pure He (a) and in (He+H2)-
plasmas when the Ion Cyclotron Resonances (ICR),
ω=4ωcHe+=2ωcD=ωcH were present in the plasma cross-
section. (Minor concentrations of the protons/deuterons in
helium plasmas were present due to hydrogen/deuterium
outgassing from the walls.) It is clearly seen that
increasing the H2/He-ratio (from 0 to 0.2) causes the
decrease in the averaged energy of both, H and D atoms.
The phenomenon observed in the ICRF plasmas was
predicted from modeling of the power deposition profiles
for plasma species of variable concentrations using the
TOMCAT code [13] and looks similar to the well-known
transition in plasma heating scenarios from dominant ion
cyclotron heating of the minority ions to heating of the
electrons via mode conversion process when
concentration of the minority ions goes up.
4. ICRF WALL CONDITIONING
In future reactor-scale superconducting fusion devices
such as ITER, the presence of permanent high magnetic
field will prevent the use of conventional Glow Discharge
Conditioning (G-DC) in between shots due to a short-
circuit occurring between anode and cathode along the
magnetic field lines. The need of controlled and
reproducible plasma start-up and tritium removal, e.g.
from the co-deposited carbon layers, will require applying
an alternative wall conditioning technique compatible
with the presence of magnetic field.
4.1. WALL CONDITIONING
IN THE PRESENT-DAY MACHINES
ICRF Discharge Conditioning (ICRF-DC) was
initially developed in stellarators [1] and successfully
applied in tokamaks later [3] using the present generation
ICRF antennas without any modifications in hardware.
The discharge conditioning is attributed to the
removal of adsorbed gas species from the wall so that
they may then be pumped out of the system. The adsorbed
atoms may be removed by electronic excitation, chemical
interaction and momentum/energy transfer [19]. For the
latter mechanism, the rate of desorption increases with the
impact energy of the ions and their masses [20]. ICRF
discharges generate high-energetic fluxes of ions and
neutrals due to presence of cyclotron mechanism (Fig.4)
and may be considered promising for wall conditioning.
Fig.5. Desorption of the gas species after a set of helium
ECRF-DC and ICRF-DC in TEXTOR: PECRF=150 kW,
f=110 GHz, PICRF=60 kW, f=32.5 MHz, BT=2.0 T,
pHe ≈ 2.5×10-2 Pa
Very optimistic results with ICRF-DC were achieved
in the limiter tokamaks. The hydrogen removal rate in the
resonance condition ω=ωcH=4ωcHe+ was found to be about
10-20 times higher than in the typical G-DC [3] and about
20 times higher than in the ECRF-DC (ω=2ωce) produced
by a focused microwave beam [3]. In the latter case
(Fig.5), better homogeneity of the ICRF discharge and
generation of the energetic neutrals bombarding the wall
could contribute to the achieved result.
The oxidation of amorphous tritiated carbon layers by
plasma-assisted technique is considered as one of the
most promising techniques to solve the problem of tritium
retention in fusion reactor [21]. A set of successful
experiments on O-treatment with ICRF discharges in the
(He+O2)-mixtures or in pure oxygen has recently been
performed on tokamaks HT-7 [22] and TEXTOR [14].
Compared to ICRF-DC in He, the ICRF oxidation
demonstrated a higher removal rate for the C-atoms by a
factor of 20 and for the H-atoms by a factor of six [22].
However, post-oxidation wall cleaning (consequence of
the residual O-retention) and inevitable phase of the
tokamak recovery to the normal plasma operation
(accompanied by contamination caused disruptions) look
at the moment as time consuming and painful procedures:
from ten to several tens disruptive shots are needed for
tokamak recovery [14,22].
10
10
10
10
10
10
- 5
- 4
- 3
- 2
- 1
0
1 2 3 4 5 1 2 3 4 5
ECRF-DC ICRF-DC
H2
H2
HD
H2O
CO
CO2
Shots
10
m
in
G
lo
w
-D
C
in
H
2
10
m
in
G
lo
w
-D
C
in
H
2
33
The encouraging result with ICRF-DC in (N2+H2)-
mixture has recently been obtained in the URAGAN-3M
(U-3M) stellarator [23]: surprisingly high removal rate of
hydrogen. This effect was explained by increased
interactions of the adsorbed hydrogen with neutrals and
different radicals like NH(NH+), NH2(NH2
+) produced in
the (N2+H2)-plasmas. Chemical erosion of the C
containing amorphous a-C: H films with the nitride ions
followed by the formation of volatile hydrocarbons could
be another probable mechanism responsible for the
enhanced hydrogen removal [24].
4.2. MODELING OF ICRF CONDITIONING
PLASMAS IN ITER
The simulation of hydrogen conditioning plasmas with
the low Te≈1 eV and ionization degree (1.0−16%) was
done for the ITER-like case ( pla ≈2.6 m, R0=6.2 m,
BT=5.3 T) using recently developed 0-D plasma code based
on the electron collisional ionization with the updated
reaction rates [7]. Two extreme cases with the low power-
per-particle, )mkW/(Pa13 3⋅≈N/P , and the high power-
per-particle, )mkW/(Pa200 3⋅≈N/P , have been analyzed.
Fig.6. 0-D simulation of the hydrogen conditioning
plasma in ITER for the low power-per-particle case
(P/N~13 kW/(Pa·m3)
In the first case (Fig.6), the code predicts that weakly
ionized (γi ≈1.4%) low temperature (Te≈1 eV) and low
density (ne≈4×1011 cm-3) plasma may be produced in
ITER-size machines coupling relatively low power with
the electrons (PRF-e≈850 kW). Assuming that coupling
efficiency of the ICRF system is about 50%, a relatively
low power at the RF generator (PRF-G≈1.7 MW) will be
necessary. This regime may be achieved operating at high
gas pressures (pH2≈8×10-2 Pa) and looks reasonable for
the starting phase of wall conditioning. The second
simulated regime with Te≈1.4 eV may be achieved at the
reduced gas pressure (pH2≈2×10-2 Pa) and the increased
RF power (PRF-e≈3.4 MW, PRF-G≈6.8 MW) and is
characterized by the increased ionization degree, γi ≈16%.
The RF power predicted for this regime was found in a
good agreement with direct extrapolation to ITER from
TEXTOR data assuming similar power density
(PRF-pl(TEXTOR) ≈ 50 kW à PRF-pl(ITER) ≈ 3.5 MW). Wall
conditioning at PRF/N>200 kW/(Pa·m-3) may become
economically disadvantageous (PRF-G>10 MW) and
inefficient for pumping out the adsorbed gas species
(γi>>16%).
5. ICRF ASSISTED TOKAMAK START-UP
For the present ITER start-up scenario, the inductive
electric field is limited to E0≈0.3 V/m, to prevent a
quench in the superconducting coils. Therefore, to
perform the tokamak start-up at E0≈0.3 V/m in a safe,
prompt and reliable manner, non-inductive pre-ionization,
target plasma production and pre-heating are desirable.
5.1. TEXTOR START-UP
WITH ICRF PRE-IONIZATION
ICRF-assisted tokamak start-up has successfully been
tested on tokamaks TEXTOR and HT-7. In the case of
TEXTOR [4,25], two pairs of the ICRF double-loop
antennas without FS, driven in π phase, have been used in
the standard 2ωci scenario to produce pre-heated RF
plasmas prior applying the inductive electric field. The
target helium RF plasma with density
ne≈(0.2−7.0)×1017 m-3 was reliably produced in the gas
pressure range p≈(1.5−7.0)×10-3 Pa with the total RF
power about 300 kW, applied to both antennas. ICRF-
assisted start-up was achieved at the central inductive
electric field E0 ≈ 0.32 V/m, which met the ITER
requirements (Fig.7).
Fig.7. ICRF-assisted low loop voltage start-up in
TEXTOR: BT=2.25 T, pHe≈3.5×10-3 Pa. Te2, Te4, Te9 is
resp. Te(ECE) at R=1.75, 1.56, 2.08 m
Without assistance, start-up at E0≈0.45 V/m was possible.
ICRF-assisted start-up has been found to be more prompt
and robust than a non-assisted one and has resulted in a
significantly broader (about four times) pressure range for
current initiation, with ≈22% higher current ramp-up rates.
5.2. MODELING OF ICRF PRE-IONIZATION
IN ITER
The experiments performed on TEXTOR clear
indicated that the assisted tokamak start-up at low
inductive electric field (E0≈0.32 V/m) could only be
successful when the following requirements have
simultaneously been achieved [25]:
• Low resistance of the target plasma, Rpl ≤0.4 mΩ;
• Low value of the compensated stray field, |BV| ≤10 G;
• Low content of the low-Z impurities.
Considering the mentioned requirements, simulations
with the 0-D Plasma code predicted that fully ionized
hydrogen plasma with high enough temperature
(Te ≥60 eV) might be produced in ITER-like machine with
the power coupled to the electrons less than 2 MW.
However, presence of 3% C-impurity increased the
needed power by ≈54%.
6. TARGET ICRF PLASMA PRODUCTION
IN STELLARATORS
To operate in a current-free regime, fusion machines
based on the stellarator concept usually use the non-
inductive auxiliary heating systems for target plasma
production. The plasma production technique in the ICRF
band was originally developed to achieve this goal in
Kharkov stellarators in the early 70th using Frame-Type
antennas (FTA) [5].
0.1 0.2 0.3 0.4 0.5
Time [s]
Prf-e=0.85 MW
0
0.2
0.4
0.6
0.8
1.0
P
rf-
e
[M
W
]
γ i
0
0.2
0.4
0.6
0.8
1.0
γ =1.4%
i
ne
10
6
10
8
10
10
10
12
n
[
cm
]
e
-³
0
1
2
3
T
[e
V]
Te
Ti Ta
TEXTOR: #81353
-0.3 -0.2 -0.1
TIME [s]
ne0
Vloop Ip
Te2
PRF1
Te4
Te9
p [10 Pa]He
PRF2
0
5
500
0
00
10
0
3
0.0 0.1 0.2 0.3 0.4 0.5 0.6
-3
P [kW]RF n [10 m ]18 -3
e
400
0
1.5 T [keV]e
V [V]loop I [kA]p
34
The ability of antenna to produce plasma can be
characterized by the parameter ρ =Rpl/ne (Rpl is the
antenna-plasma loading resistance), which is proportional
to the plasma production rate. The constancy of the
parameter in time provides exponential growth of the
plasma density with the same increment. Based on the
‘ρ=const’ concept, compact Three-Half-Turn (THT) and
Crankshaft-like antennas were proposed for Alfvén
Resonance plasma production and heating in U-3M [26]
(Fig.8). Target dense plasmas have successfully been
produced when the THT antenna sequentially operated
with FTA [6] (ne≈2×1019 m-3) or when the Crankshaft
antenna operated alone (ne≤1×1019 m-3) [8], in a good
agreement with predictions from modeling [26].
Numerical optimization of the Crankshaft antenna for the
RF plasma production in the U-2M stellarator is under
progress using self-consistent modeling with 1-D Plasma
and 1-D RF codes [27].
Fig.8. Calculated dependence of plasma production rate
index ρ=Rpl/ne vs. plasma density
for U-3M Crankshaft and THT antennas
REFERENCES
1. N.I. Nazarov et al.// Sov. J. Plasma Phys. 1987, v.13,
p. 871-873.
2. R. Brakel et al.// Journal of Nuclear Materials. 2001,
v. 290-293, p. 1160-1165.
3. E. de la Cal, E. Gauthier// Plasma Phys. Control. Fusion.
2005, v. 47, p. 197-218.
4. R. Koch et al.// 26th EPS Conf. Contr. Fusion and Plasma
Phys., Maastricht, 1999/ ECA, 1999, v. 23J, p. 745-748.
5. O.M. Shvets et al.// 4th Int. Symp. on Heating in Toroidal
Plasmas, Roma, 1984/ ENEA, Frascati, 1984, v.1,
p. 513-528.
6. A. Lyssoivan et al.// Fusion Engineering and Design. 1995,
v. 26, p. 185-190.
7. J. Buermans and T. Matthys // Diploma Thesis,
ERM/KMS, Brussels, 2006.
8. V.E. Moiseenko // 7th Int. Conf. on Plasma Phys. and
Control. Fusion, Alushta, 1998, Paper I-5.
9. A. Lyssoivan et al.// Journal of Nuclear Materials. 2005,
v. 337-339, p. 456-460.
10. A.I. Lyssoivan et al.// Nuclear Fusion. 1992, v. 32,
p. 1361-1372.
11. A. Lyssoivan et al.// Final Report on ITER Design Task
D350.2. LPP-ERM/KMS Laboratory, Brussels, 1998,
Report N114.
12. A. Lyssoivan et al.// Problems of Atomic Sci. and Technol.
Series “Plasma Physics” (10). 2005, N 1, p. 44-48.
13. D. Van Eester, R. Koch// Plasma Phys. Control. Fusion .
1998, v. 40, p. 1949.
14. A. Lyssoivan et al.// 17th Int. Conf. Plasma Surface
Interactions, Hefei, 2006, Paper P2-72.
15. A. Lyssoivan et al.// 16th Topic. Conf. on Radio Frequency
Power in Plasmas, Park City, 2005/ AIP, 2005, v. 787,
p. 445-448.
16. A. Lyssoivan et al.// 14th Topic. Conf. on Radio Frequency
Power in Plasmas, Oxnard, 2001/ AIP 2001, v. 595,
p. 146-149.
17. A. Lyssoivan et al.// 26th EPS Conf. Contr. Fusion and
Plasma Phys., Maastricht, 1999/ ECA, 1999, v. 23J,
p. 737-740.
18. R. Koch // Transactions of Fusion Science and Technology.
2004, v. 45, p. 203.
19. P.C. Stangeby, G.M. McCracken// Nuclear Fusion. 1990,
v. 30, p. 1225-1379.
20. J. Winter // Plasma Phys. Control. Fusion. 1996, v. 38,
p. 1503-1542.
21. J. Davis, A.A. Haasz // Phys. Scripta. 2001, v.T91, p.33-35.
22. J.S. Hu et al.// 17th Int. Conf. Plasma Surface Interactions,
Hefei, 2006, Paper I-16.
23. G.P. Glazunov et al. // Problems of Atomic Sci. and
Technol. Series “Plasma Physics” (10). 2005, N1, p.33-35.
24. V.S. Vojtsenya et al. // Problems of Atomic Sci. and
Technol. Series “Plasma Physics” (12). 2006, N6, p.141.
25. R. Koch et al.// 16th Int. Conf. on FusionEnergy, Montreal,
1996/ IAEA, 1997, v.1, p. 633-641.
26. V.E. Moiseenko et al.// 21st EPS Conf. on Contr. Fusion
and Plasma Phys., Montpellier, 1994/ ECA, 1994, v.18B,
p. 980-983.
27. V.E. Moiseenko et al.// Problems of Atomic Sci. and
Technol. Series “Plasma Physics” (12). 2006, N 6, p. 62.
. , . , . , . , . , M. , . , . ,
T. Ma , . , O. M , O. , . , . , . , .- . ,
.A. , A. , .-M. , . , . , . , . , A. . ,
.E. Mo , . †, O.M. , K. . , E. . , . , .A. ,
TEXTOR, ASDEX Upgrade, TORE SUPRA U-3M
(ICRF)
: (i)
; (ii) A
(E0 ~ 0.3 ITER ); (iii) (ne ≥1019 -3) .
.
0-D ITER .
. , . , . , . , . , M. , . , . ,
T. Ma , . , O. M , O. , . , . , . , .- . ,
.A. , A. , .-M. , . , . , . , . , . ,
. Mo , . †, O.M. , K. . , . , . , .A. ,
TEXTOR, ASDEX Upgrade, TORE SUPRA U-3M
(ICRF)
: (i)
; (ii) A (E0~ 0.3
ITER ); (iii) (ne ≥1019 -3) .
. 0-D
ITER .
106 108 1010 1012 1014
10-12
10-14
10-16
10-18
ρ
n [cm ]e
-3
Crankshaft
THT
|
| id | nasplib_isofts_kiev_ua-123456789-110347 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-11-27T18:32:46Z |
| publishDate | 2007 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Lyssoivan, A. Koch, R. Van Eester, D. Van Schoor, M. Van Wassenhove, G. Vervier, M. Weynants, R. Buermans, J. Matthys, T. Esser, H.G. Marchuk, O. Neubauer, O. Philipps, V. Sergienko, G. Bobkov, V. Fahrbach, H.-U. Hartmann, D.A. Herrmann, A. Noterdaeme, J.-M. Rohde, V. Beaumont, B. Gauthier, E. Glazunov, G.P. Lozin, A.V. Moiseenko, V.E. Nazarov, N.I. Shvets, O.M. Stepanov, K.N. Volkov, E.D. Beigman, I.L. Vainshtein, L.A. 2017-01-03T16:33:01Z 2017-01-03T16:33:01Z 2007 ICRF plasmas for fusion reactor applications / A. Lyssoivan, R. Koch, D. Van Eester, M. Van Schoor, G. Van Wassenhove, M. Vervier, R. Weynants, J. Buermans, T. Matthys, H.G. Esser, O. Marchuk, O. Neubauer, V. Philipps, G. Sergienko, V. Bobkov, H.-U. Fahrbach, D.A. Hartmann, A. Herrmann, J.-M. Noterdaeme, V. Rohde, B. Beaumont, E. Gauthier, G.P. Glazunov, A.V. Lozin, V.E. Moiseenko, N.I. Nazarov, O.M. Shvets, K.N. Stepanov, E.D. Volkov, I.L. Beigman, L.A. Vainshtein // Вопросы атомной науки и техники. — 2007. — № 1. — С. 30-34. — Бібліогр.: 27 назв. — англ. 1562-6016 PACS: 52.25.Jm, 52.35.Hr, 52.40.Fd, 52.40.Hf, 52.50.Qt https://nasplib.isofts.kiev.ua/handle/123456789/110347 The ICRF plasma production technique is considered as a promising alternative tool for the following applications in the present and next generation superconducting fusion devices: (i) Wall conditioning in the presence of permanent high magnetic field; (ii) Assistance for the tokamak start-up at low inductive electric field (E₀ ~ 0.3 V/m in ITER); (iii) Target dense plasma production (ne ≥ 10¹⁹ m⁻³) in stellarators. The paper presents a review of the ICRF plasma production technique and its applications in the present-day tokamaks and stellarators. The perspective of the alternative technique applications in ITER is analyzed in the frame of 0-D plasma modeling. ВЧ-метод утворення плазми (ICRF) розглядається як перспективний альтернативний інструмент для таких застосувань у сучасних й майбутніх надпровідних термоядерних установках: (i) ВЧ-чистка стінок в присутності постійного сильного магнітного поля; (ii) Aсистування старту токамака у режимі слабого вихрового електричного поля (E₀~ 0.3 В/м в ITERі); (iii) Створення густої вихідної плазми (ne ≥ 10¹⁹ м⁻³) в стелараторах. Зроблено огляд ВЧ-метода створення плазми та його застосування у сучасних токамаках й стелараторах. В рамках моделювання 0-D плазмовим кодом проведено аналіз перспективності використання даного метода в ITERі. ВЧ-метод создания плазмы (ICRF) рассматривается как перспективный альтернативный инструмент для следующих применений в современных и будущих сверхпроводящих термоядерных установках: (i) ВЧ-чистка стенок в присутствии постоянного сильного магнитного поля; (ii) Aссистирование старту токамака в режиме слабого вихревого электрического поля (E₀ ~ 0.3 В/м в ITERе); (iii) Создание плотной исходной плазмы (ne ≥ 10¹⁹ м⁻³) в стеллараторах. Сделан обзор ВЧ-метода создания плазмы и его применений в современных токамаках и стеллараторах. В рамках моделирования 0-D плазменным кодом проведен анализ перспективности использования данного метода в ITERе. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники ITER and fusion reactor aspects ICRF plasmas for fusion reactor applications Застосування ВЧ-плазми у термоядерному реакторі Применение ВЧ-плазмы в термоядерном реакторе Article published earlier |
| spellingShingle | ICRF plasmas for fusion reactor applications Lyssoivan, A. Koch, R. Van Eester, D. Van Schoor, M. Van Wassenhove, G. Vervier, M. Weynants, R. Buermans, J. Matthys, T. Esser, H.G. Marchuk, O. Neubauer, O. Philipps, V. Sergienko, G. Bobkov, V. Fahrbach, H.-U. Hartmann, D.A. Herrmann, A. Noterdaeme, J.-M. Rohde, V. Beaumont, B. Gauthier, E. Glazunov, G.P. Lozin, A.V. Moiseenko, V.E. Nazarov, N.I. Shvets, O.M. Stepanov, K.N. Volkov, E.D. Beigman, I.L. Vainshtein, L.A. ITER and fusion reactor aspects |
| title | ICRF plasmas for fusion reactor applications |
| title_alt | Застосування ВЧ-плазми у термоядерному реакторі Применение ВЧ-плазмы в термоядерном реакторе |
| title_full | ICRF plasmas for fusion reactor applications |
| title_fullStr | ICRF plasmas for fusion reactor applications |
| title_full_unstemmed | ICRF plasmas for fusion reactor applications |
| title_short | ICRF plasmas for fusion reactor applications |
| title_sort | icrf plasmas for fusion reactor applications |
| topic | ITER and fusion reactor aspects |
| topic_facet | ITER and fusion reactor aspects |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/110347 |
| work_keys_str_mv | AT lyssoivana icrfplasmasforfusionreactorapplications AT kochr icrfplasmasforfusionreactorapplications AT vaneesterd icrfplasmasforfusionreactorapplications AT vanschoorm icrfplasmasforfusionreactorapplications AT vanwassenhoveg icrfplasmasforfusionreactorapplications AT vervierm icrfplasmasforfusionreactorapplications AT weynantsr icrfplasmasforfusionreactorapplications AT buermansj icrfplasmasforfusionreactorapplications AT matthyst icrfplasmasforfusionreactorapplications AT esserhg icrfplasmasforfusionreactorapplications AT marchuko icrfplasmasforfusionreactorapplications AT neubauero icrfplasmasforfusionreactorapplications AT philippsv icrfplasmasforfusionreactorapplications AT sergienkog icrfplasmasforfusionreactorapplications AT bobkovv icrfplasmasforfusionreactorapplications AT fahrbachhu icrfplasmasforfusionreactorapplications AT hartmannda icrfplasmasforfusionreactorapplications AT herrmanna icrfplasmasforfusionreactorapplications AT noterdaemejm icrfplasmasforfusionreactorapplications AT rohdev icrfplasmasforfusionreactorapplications AT beaumontb icrfplasmasforfusionreactorapplications AT gauthiere icrfplasmasforfusionreactorapplications AT glazunovgp icrfplasmasforfusionreactorapplications AT lozinav icrfplasmasforfusionreactorapplications AT moiseenkove icrfplasmasforfusionreactorapplications AT nazarovni icrfplasmasforfusionreactorapplications AT shvetsom icrfplasmasforfusionreactorapplications AT stepanovkn icrfplasmasforfusionreactorapplications AT volkoved icrfplasmasforfusionreactorapplications AT beigmanil icrfplasmasforfusionreactorapplications AT vainshteinla icrfplasmasforfusionreactorapplications AT lyssoivana zastosuvannâvčplazmiutermoâdernomureaktorí AT kochr zastosuvannâvčplazmiutermoâdernomureaktorí AT vaneesterd zastosuvannâvčplazmiutermoâdernomureaktorí AT vanschoorm zastosuvannâvčplazmiutermoâdernomureaktorí AT vanwassenhoveg zastosuvannâvčplazmiutermoâdernomureaktorí AT vervierm zastosuvannâvčplazmiutermoâdernomureaktorí AT weynantsr zastosuvannâvčplazmiutermoâdernomureaktorí AT buermansj zastosuvannâvčplazmiutermoâdernomureaktorí AT matthyst zastosuvannâvčplazmiutermoâdernomureaktorí AT esserhg zastosuvannâvčplazmiutermoâdernomureaktorí AT marchuko zastosuvannâvčplazmiutermoâdernomureaktorí AT neubauero zastosuvannâvčplazmiutermoâdernomureaktorí AT philippsv zastosuvannâvčplazmiutermoâdernomureaktorí AT sergienkog zastosuvannâvčplazmiutermoâdernomureaktorí AT bobkovv zastosuvannâvčplazmiutermoâdernomureaktorí AT fahrbachhu zastosuvannâvčplazmiutermoâdernomureaktorí AT hartmannda zastosuvannâvčplazmiutermoâdernomureaktorí AT herrmanna zastosuvannâvčplazmiutermoâdernomureaktorí AT noterdaemejm zastosuvannâvčplazmiutermoâdernomureaktorí AT rohdev zastosuvannâvčplazmiutermoâdernomureaktorí AT beaumontb zastosuvannâvčplazmiutermoâdernomureaktorí AT gauthiere zastosuvannâvčplazmiutermoâdernomureaktorí AT glazunovgp zastosuvannâvčplazmiutermoâdernomureaktorí AT lozinav zastosuvannâvčplazmiutermoâdernomureaktorí AT moiseenkove zastosuvannâvčplazmiutermoâdernomureaktorí AT nazarovni zastosuvannâvčplazmiutermoâdernomureaktorí AT shvetsom zastosuvannâvčplazmiutermoâdernomureaktorí AT stepanovkn zastosuvannâvčplazmiutermoâdernomureaktorí AT volkoved zastosuvannâvčplazmiutermoâdernomureaktorí AT beigmanil zastosuvannâvčplazmiutermoâdernomureaktorí AT vainshteinla zastosuvannâvčplazmiutermoâdernomureaktorí AT lyssoivana primenenievčplazmyvtermoâdernomreaktore AT kochr primenenievčplazmyvtermoâdernomreaktore AT vaneesterd primenenievčplazmyvtermoâdernomreaktore AT vanschoorm primenenievčplazmyvtermoâdernomreaktore AT vanwassenhoveg primenenievčplazmyvtermoâdernomreaktore AT vervierm primenenievčplazmyvtermoâdernomreaktore AT weynantsr primenenievčplazmyvtermoâdernomreaktore AT buermansj primenenievčplazmyvtermoâdernomreaktore AT matthyst primenenievčplazmyvtermoâdernomreaktore AT esserhg primenenievčplazmyvtermoâdernomreaktore AT marchuko primenenievčplazmyvtermoâdernomreaktore AT neubauero primenenievčplazmyvtermoâdernomreaktore AT philippsv primenenievčplazmyvtermoâdernomreaktore AT sergienkog primenenievčplazmyvtermoâdernomreaktore AT bobkovv primenenievčplazmyvtermoâdernomreaktore AT fahrbachhu primenenievčplazmyvtermoâdernomreaktore AT hartmannda primenenievčplazmyvtermoâdernomreaktore AT herrmanna primenenievčplazmyvtermoâdernomreaktore AT noterdaemejm primenenievčplazmyvtermoâdernomreaktore AT rohdev primenenievčplazmyvtermoâdernomreaktore AT beaumontb primenenievčplazmyvtermoâdernomreaktore AT gauthiere primenenievčplazmyvtermoâdernomreaktore AT glazunovgp primenenievčplazmyvtermoâdernomreaktore AT lozinav primenenievčplazmyvtermoâdernomreaktore AT moiseenkove primenenievčplazmyvtermoâdernomreaktore AT nazarovni primenenievčplazmyvtermoâdernomreaktore AT shvetsom primenenievčplazmyvtermoâdernomreaktore AT stepanovkn primenenievčplazmyvtermoâdernomreaktore AT volkoved primenenievčplazmyvtermoâdernomreaktore AT beigmanil primenenievčplazmyvtermoâdernomreaktore AT vainshteinla primenenievčplazmyvtermoâdernomreaktore |