Magnetic field distribution in plasma shield during high-power plasma stream target interaction
The distributions of magnetic field in the shielding plasma layers, created during the powerful plasma stream interaction with the graphite sample were carried out. Plasma streams, generated by plasma accelerator QSPA Kh- 50, irradiated graphite targets of 5,13 and 22cm in diameter in longitudinal m...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2000
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| Cite this: | Magnetic field distribution in plasma shield during high-power plasma stream target interaction / V.V. Chebotarev, I.E. Garkusha, V.A. Makhlaj, N.I. Mitina, D.G. Solyakov, V.I. Tereshin, S.A. Trubchaninov, A.V. Tsarenko, H. Wuerz // Вопросы атомной науки и техники. — 2000. — № 6. — С. 100-102. — Бібліогр.: 3 назв. — англ. |
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Chebotarev, V.V. Garkusha, I.E. Makhlaj, V.A. Mitina, N.I. Solyakov, D.G. Tereshin, V.I. Trubchaninov, S.A. Tsarenko, A.V. Wuerz, H. 2015-03-18T19:21:05Z 2015-03-18T19:21:05Z 2000 Magnetic field distribution in plasma shield during high-power plasma stream target interaction / V.V. Chebotarev, I.E. Garkusha, V.A. Makhlaj, N.I. Mitina, D.G. Solyakov, V.I. Tereshin, S.A. Trubchaninov, A.V. Tsarenko, H. Wuerz // Вопросы атомной науки и техники. — 2000. — № 6. — С. 100-102. — Бібліогр.: 3 назв. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/78560 533.9 The distributions of magnetic field in the shielding plasma layers, created during the powerful plasma stream interaction with the graphite sample were carried out. Plasma streams, generated by plasma accelerator QSPA Kh- 50, irradiated graphite targets of 5,13 and 22cm in diameter in longitudinal magnetic field of strength up to 0.54 T. It was shown that distributions of the magnetic field in front of sample were strongly depended on the target diameter. The value of magnetic field displacement from the target plasma was increased with decreasing the target diameter (the magnetic field displacement achieved 0.135T for the target diameter of 5 cm and 0.46 T the target with diameter of 22 cm). The size of the shielding layer in radial direction was determined by a flow of plasma stream around the target. This work was partly supported by the Science and Technology Center in Ukraine (STCU), Grant #881, and Ministry of Education and Science of Ukraine, International Collaboration, Grant #2M/92-2000 en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Plasma dynamics and plasma-wall interaction Magnetic field distribution in plasma shield during high-power plasma stream target interaction Article published earlier |
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Magnetic field distribution in plasma shield during high-power plasma stream target interaction |
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Magnetic field distribution in plasma shield during high-power plasma stream target interaction Chebotarev, V.V. Garkusha, I.E. Makhlaj, V.A. Mitina, N.I. Solyakov, D.G. Tereshin, V.I. Trubchaninov, S.A. Tsarenko, A.V. Wuerz, H. Plasma dynamics and plasma-wall interaction |
| title_short |
Magnetic field distribution in plasma shield during high-power plasma stream target interaction |
| title_full |
Magnetic field distribution in plasma shield during high-power plasma stream target interaction |
| title_fullStr |
Magnetic field distribution in plasma shield during high-power plasma stream target interaction |
| title_full_unstemmed |
Magnetic field distribution in plasma shield during high-power plasma stream target interaction |
| title_sort |
magnetic field distribution in plasma shield during high-power plasma stream target interaction |
| author |
Chebotarev, V.V. Garkusha, I.E. Makhlaj, V.A. Mitina, N.I. Solyakov, D.G. Tereshin, V.I. Trubchaninov, S.A. Tsarenko, A.V. Wuerz, H. |
| author_facet |
Chebotarev, V.V. Garkusha, I.E. Makhlaj, V.A. Mitina, N.I. Solyakov, D.G. Tereshin, V.I. Trubchaninov, S.A. Tsarenko, A.V. Wuerz, H. |
| topic |
Plasma dynamics and plasma-wall interaction |
| topic_facet |
Plasma dynamics and plasma-wall interaction |
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2000 |
| language |
English |
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Вопросы атомной науки и техники |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Article |
| description |
The distributions of magnetic field in the shielding plasma layers, created during the powerful plasma stream interaction with the graphite sample were carried out. Plasma streams, generated by plasma accelerator QSPA Kh- 50, irradiated graphite targets of 5,13 and 22cm in diameter in longitudinal magnetic field of strength up to 0.54 T. It was shown that distributions of the magnetic field in front of sample were strongly depended on the target diameter. The value of magnetic field displacement from the target plasma was increased with decreasing the target diameter (the magnetic field displacement achieved 0.135T for the target diameter of 5 cm and 0.46 T the target with diameter of 22 cm). The size of the shielding layer in radial direction was determined by a flow of plasma stream around the target.
|
| issn |
1562-6016 |
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https://nasplib.isofts.kiev.ua/handle/123456789/78560 |
| citation_txt |
Magnetic field distribution in plasma shield during high-power plasma stream target interaction / V.V. Chebotarev, I.E. Garkusha, V.A. Makhlaj, N.I. Mitina, D.G. Solyakov, V.I. Tereshin, S.A. Trubchaninov, A.V. Tsarenko, H. Wuerz // Вопросы атомной науки и техники. — 2000. — № 6. — С. 100-102. — Бібліогр.: 3 назв. — англ. |
| work_keys_str_mv |
AT chebotarevvv magneticfielddistributioninplasmashieldduringhighpowerplasmastreamtargetinteraction AT garkushaie magneticfielddistributioninplasmashieldduringhighpowerplasmastreamtargetinteraction AT makhlajva magneticfielddistributioninplasmashieldduringhighpowerplasmastreamtargetinteraction AT mitinani magneticfielddistributioninplasmashieldduringhighpowerplasmastreamtargetinteraction AT solyakovdg magneticfielddistributioninplasmashieldduringhighpowerplasmastreamtargetinteraction AT tereshinvi magneticfielddistributioninplasmashieldduringhighpowerplasmastreamtargetinteraction AT trubchaninovsa magneticfielddistributioninplasmashieldduringhighpowerplasmastreamtargetinteraction AT tsarenkoav magneticfielddistributioninplasmashieldduringhighpowerplasmastreamtargetinteraction AT wuerzh magneticfielddistributioninplasmashieldduringhighpowerplasmastreamtargetinteraction |
| first_indexed |
2025-11-25T21:33:36Z |
| last_indexed |
2025-11-25T21:33:36Z |
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1850559575230513152 |
| fulltext |
100 Problems of Atomic Science and Technolog
UDC 533.9
MAGNETIC FIELD DISTRIBUTIONS IN A PLASMA SHIELD LAYER
DURING HIGH-POWER PLASMA STREAM-TARGET INTERACTION
V.V.Chebotarev, I.E.Garkusha, V.A.Makhlaj, N.I.Mitina, D.G.Solyakov, V.I.Tereshin,
S.A.Trubchaninov, A.V.Tsarenko, and H. Wuerz*
Institute of Plasma Physics of the National Science Center “Kharkov Institute of Physics
and Technology”, Akademicheskaya St., 1, 61108 Kharkov,Ukraine,
*)Forschugszentrum Karlsruhe, IHM, Postfach 3640, D-76021, Karlsruhe, Germany
The distributions of magnetic field in the shielding plasma layers, created during the powerful plasma stream
interaction with the graphite sample were carried out. Plasma streams, generated by plasma accelerator QSPA Kh-
50, irradiated graphite targets of 5,13 and 22cm in diameter in longitudinal magnetic field of strength up to 0.54 T.
It was shown that distributions of the magnetic field in front of sample were strongly depended on the target
diameter. The value of magnetic field displacement from the target plasma was increased with decreasing the target
diameter (the magnetic field displacement achieved 0.135T for the target diameter of 5 cm and 0.46 T the target
with diameter of 22 cm). The size of the shielding layer in radial direction was determined by a flow of plasma
stream around the target.
1. Introduction
During the thermal phase of tokamak plasma
disruption the divertor plates are heated by the intense
plasma streams. To simulate the processes that can be
occurred on the divertor plates surface during their
bombardment with plasma the powerful magnetized
plasma streams, generated by the QSPA (quasi-steady-
state plasma accelerator), can be used.
It was shown earlier that shielding plasma layers of
high density were formed near the surface of target
irradiated with the powerful plasma streams. At the
process of the plasma streams interaction with a target
placed in magnetic field the latter was displaced from
the shielding plasma layer. This effect of strong
magnetic field displacement by the plasma might play
an important role at the process of the energy deliver to
the sample surface and plasma stability of shield layer.
The results of the measurements and analysis of
distributions of the magnetic field at the near-surface
region of the graphite target, irradiated with magnetized
plasma streams are presented in this paper. The full-
block quasi-steady-state plasma accelerator QSPA Kh-
50 was used as the plasma streams source [1].
2. Experimental installation
The plasma streams were injected into a magnetic
solenoid of 1.6 m in length and 0.44 m in inner
diameter. The magnetic solenoid consists of 4 separate
magnetic coils. The vacuum chamber of magnetic
solenoid was joined by means of the conical input and
output chambers with the main vacuum chamber of the
QSPA device. The magnetic field strength achieved
0.54 T. The parameters of the plasma streams flowing in
the magnetic solenoid were as follow: the plasma stream
density - (1-3)·1016 cm-3, maximum power density 20
MW/cm2, maximum proton energy 200 eV, power pulse
duration (150-170) µs, average β ≈ (0.1÷0.2) [2].
The distributions of the magnetic fields in front of
the target were measured by the local movable magnetic
probe with the maximum diameter of 6 mm. The
magnetic probe was located at the distance of 2.3 m
from the accelerator QSPA Kh-50 output [2].
For measurements of the magnetic field distributions
at the different distances from the target surface a
special system for target displacement along the axis of
the vacuum camber was utilized. This system consists
of a cog-wheel, a rack and a supporting bar. It was
placed inside the output conical vacuum chamber of the
QSPA Kh-50 device. The minimum distance between
the accelerator output and the target position was 2.25 m
and the maximum one - 2.7 m (the maximum spacing of
measurements was 45 cm). The scheme of experiments
is presented in the Fig.1.
a
chamber of magnetic solenoid
displacement
chamber chamber
Diagnostic chamber
Magnetic coil
System for target
Z=2.7m
Z=2.25m
Plasma stream
output conical input conical
Magnetic probe
Fig.1. The scheme of experiment
y. 2000. № 6. Series: Plasma Physics (6). p. 100-102
The MPG -7 graphite targets with diameter of 5, 13
nd 22cm were used.
101
3. The magnetic field distributions at the
vicinity of a target
The radial distributions of the magnetic field were
measured for the different distances from the target
surface and for the different moments of time. The
measured radial distributions of the magnetic field in
plasma shield, normalized by the value of a vacuum
magnetic field, are shown in Figs. 2, 3, 4 and 5 for the
moment of time of (170-180) µs. This moment
corresponds to the maximum power density in the
plasma streams, generated by the QSPA device [2].
One can see the presence of a local minimum of the
magnetic field in the plasma at the radius R = 8 cm for
the target with a diameter of 5 cm and at the radius (13-
14) cm for the target with a diameter of 13 cm (Fig. 2
and 3). This local minimum was caused by plasma
flowing around the target. The coordinate of this local
minimum of the magnetic field (local minimum outside
the target) moves outward the axis with increasing the
target diameter.
0 5 10 15 20
0,0
0,2
0,4
0,6
0,8
1,0
1,2
L=1cm
L=7cm
L=20cm
B pl
as
m
a /
B z0
R, cm
Fig.2 The radial distributions of the normalized
magnetic field at the different distances from the
target with the diameter of 5 cm
0 5 10 15 20
0,0
0,2
0,4
0,6
0,8
1,0
1,2
B pl
as
m
a/B
z0
L=3cm
L=7cm
L=20cm
R, cm
Fig.3. The radial distributions of the normalized
magnetic field at the different distances from the
target with the diameter of 13 cm
The value of the magnetic field minimum was decreased
with increasing the target diameter. The local minimum
in the radial distributions of the magnetic field near the
target with diameter 22 cm was not found (Fig. 4).
Thus, the maximum radius of the plasma shield
(radius of the plasma shield is the point where Bplasma =
Bz0) was decreased with increasing the target diameter
from 12-13 cm (for the target diameter of 5 cm) down to
(7-8) cm (for the diameter of 22 cm).
The radial distributions of the magnetic field at the
distance l = 0,5 cm from the targets surface are also not
monotonous and have two extremums (Fig.5). The
existence of two local maximum in the dependence of
the magnetic field can be explained by interaction of
incoming plasma stream with the magnetic field of the
skin current, generated at surface of the target.
0 5 10 15 20
0,0
0,2
0,4
0,6
0,8
1,0
1,2
L=7cm
L=12cm
L=20cm
B pl
as
m
a/B
z0
R,cm
Fig.4. The radial distributions of the normalized
magnetic field at the different distances from the
target with the diameter of 22 cm
0 5 10 15 20
0,0
0,2
0,4
0,6
0,8
1,0
1,2
Distance from target L=0.5 cm
Diameter of target 5 cm
Diameter of target 13 cm
Diameter of target 22 cm
B pl
as
m
a/B
z0
R,cm
Fig.5.The radial distributions of the normalized
magnetic field at the distance of 0.5 cm from the
targets with diameters of 5,13 and 22 cm
It was shown in present experiments that the
magnetic field in the plasma shield is in strong
dependence on both the target diameter and the distance
from its surface. The dependencies of magnetic field in
plasma, normalized by the vacuum magnetic field, on
the distance from the target surface are shown in Fig. 6.
0 5 10 15 20 25 30
0,0
0,2
0,4
0,6
0,8
1,0
Diameter of target 5cm
Diameter of target 13cm
Diameter of target 22cm
B pl
as
m
a /
B
z0
Distance from the target, cm
Fig.6. The dependencies of the magnetic field in a
plasma, normalized by the vacuum magnetic field, on
the distance from the target surface
102
It follows from this picture that the magnetic field in
the plasma shield is increased with increasing the
distance from the target. The minimum value of
magnetic field was found in front of the target at the
distance L = (1÷3) cm from its surface. The magnetic
field in this region of the shielding plasma layer is
increased with increasing the target diameter from
0.25xBz0 = 0.135 T (for the target diameter of 5 cm) up
to 0.85xBz0 = 0.46 T (for the diameter of 22 cm). The
effect of the target presence was seen in the
distributions of the magnetic field in the shielding layer
measured up to the distances of 20 cm from the surface
of the sample (Fig. 6).
The magnetic measurements carried out inside and
behind the graphite target had shown that the magnetic
field force lines are frozen into the target. The value of
the magnetic field inside and behind of the target with
the diameter of 13 cm was up to 0.95xBz0 (Fig.7).
-6 -4 -2 0 2 4 6
0,0
0,2
0,4
0,6
0,8
1,0
G raphite target Plasm a stream
B pl
as
m
a/B
z0
D istance from the target, cm
Diametr of target 13 cm
Fig.7. The dependencies of the magnetic field in a
plasma, normalized by the vacuum magnetic field, on
the distance from the target surface
4. Discussion and conclusions
An ordinary pressure balance equation was used for
an estimation of the maximum value of the plasma
temperature Tplasma = (Te+Ti):
dS
rB
S
dS
rB
dSrTrn
S
vacuumR
R
vacuum
vacuum
R R
plasma
plasma
∫∫ ∫ =
+
*
* *
8
)(1
8
)(
)()(
1 2
0 0
2
ππ
Here: Splasma – the square of the plasma stream cross-
section; Svacuum – the square of cross-section between the
wall of a vacuum chamber and the plasma boundary;
Bplasma – the magnetic field in a plasma; R* radius of the
plasma boundary; Bvacuum – the magnetic field with no
plasma; n(r) – the radial distribution of the plasma
density; T(r) – the radial distribution of the plasma
temperature. The radial distributions of the plasma
density and temperature are approximated as follows:
−= *0 1)(
R
rnrn
−= *0 1)(
R
rTrT
Here n0 – the plasma density at R = 0 and T0 – the
plasma temperature at R = 0. These distributions were
chosen as far as the linear (or very close to linear)
dependence of the plasma density on the radius was
measured in our previous experiments with using the
interferometer with a large area of view [3]. The
experimental data of the radial distributions of the
magnetic field and the n0 value, evaluated by Stark
broadening of the Hβ spectral line at the different
distances from the target surface were used for an
estimation of the average plasma temperance.
The estimations of the plasma temperature were
performed for the distance from the sample where the
minimum magnetic field in the plasma shield exists.
The results of the plasma temperature estimation (with
using pressure balance equation) for the targets of the
different diameters are shown in the table.
Tab1e. The parameters of the shielding plasma
Diameter of the target, cm 5 13 22
Distance from the target, cm 1 2-3 2-4
Magnetic field , kG 1.35 3.24 4.6
Pressure in the shielding
plasma layer, x1017, eV/cm-3
4,8 1,9 2,2
Plasma density, x1016, cm-3 17 10 20
Tplasma = (Te + Ti), eV 16-17 11-12 7
On the base of these determinations of the electron
temperature the degree of the plasma shield
magnetization was estimated. The local plasma
temperature (Te + TI) in the near-axis region, estimated
from the pressure balance equation, was about (15-20)
eV for the target with the diameter of 5 cm. It was
decreased up to 6-7 eV with increasing the target
diameter up to 22 cm.
It is well known that the plasma is magnetized and
can’t be moved across the magnetic field lines for the
parameter ωeτe >> 1. In our experiments the Hall
parameter ωeτe was about 0.4-0.5 for all targets. In this
case the plasma shield can propagate across the
magnetic field lines.
Thus, the obtained experimental results showed that
the distributions of the magnetic field in the plasma
shield are strongly depended on the both the target
diameter and the distance from its surface. The plasma
flowing around the target is the reason for the local
minimum magnetic field presence in the plasma shield.
This work was partly supported by the Science and
Technology Center in Ukraine (STCU), Grant #881, and
Ministry of Education and Science of Ukraine,
International Collaboration, Grant #2M/92-2000.
References
[1]. O.S.Pavlichenko, V.I.Tereshin, V.V.Chebotarev et.
al. // Plasma Devices and Operations, Vol. 2, 1992,
pp.155-165.
[2]. V.I.Tereshin, V.V.Chebotarev, H.Wuerz at al. //
Problems of Atomic Science and Technology. Series
«Plasma physics» 3(3)-4(4), 1999, р. 194.
[3]. V.I.Tereshin, V.V.Chebotarev, H.Wuerz at al. //
Problems of Atomic Science and Technology. Series
«Physics of radiation damage and radiation science of
materials» 1(65) , 2(66), 1997, р. 165.
References
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