Highlights of dense magnetized plasma research in Poland
This invited lecture presents the most important achievements of theoretical and experimental studies which concerned dense magnetized plasmas and were performed in Poland during recent few years. Those studies were concentrated on high-current pulse discharges within the large mega-joule PF-1000 fa...
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| Cite this: | Highlights of dense magnetized plasma research in Poland / M.J. Sadowski, M. Scholz // Вопросы атомной науки и техники. — 2010. — № 6. — С. 194-198. — Бібліогр.: 22 назв. — англ. |
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Sadowski, M.J. Scholz, M. 2011-02-26T23:17:08Z 2011-02-26T23:17:08Z 2010 Highlights of dense magnetized plasma research in Poland / M.J. Sadowski, M. Scholz // Вопросы атомной науки и техники. — 2010. — № 6. — С. 194-198. — Бібліогр.: 22 назв. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/17502 This invited lecture presents the most important achievements of theoretical and experimental studies which concerned dense magnetized plasmas and were performed in Poland during recent few years. Those studies were concentrated on high-current pulse discharges within the large mega-joule PF-1000 facility, which was operated at the IPPLM in Warsaw and investigated by researchers from the IPJ and IPPLM. The machine was operated mainly with a pure D2 filling, and the peak discharge current amounted to 1,5...1,8 MA. Theoretical studies concerned motions of accelerated primary deuterons and fusion-produced protons. Experimental investigations included a multi-frame laser interferometry, measurements of neutron yields, optical spectroscopy of plasma streams, diagnostics of fast electronand ion-streams, and measurements of an angular distribution of fusion protons. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Диагностика плазмы Highlights of dense magnetized plasma research in Poland ОСновные достижения в исследованиях плотной замагниченной плазмы в Польше Article published earlier |
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Highlights of dense magnetized plasma research in Poland |
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Highlights of dense magnetized plasma research in Poland Sadowski, M.J. Scholz, M. Диагностика плазмы |
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Highlights of dense magnetized plasma research in Poland |
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Highlights of dense magnetized plasma research in Poland |
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Highlights of dense magnetized plasma research in Poland |
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Highlights of dense magnetized plasma research in Poland |
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highlights of dense magnetized plasma research in poland |
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Sadowski, M.J. Scholz, M. |
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Sadowski, M.J. Scholz, M. |
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Диагностика плазмы |
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ОСновные достижения в исследованиях плотной замагниченной плазмы в Польше |
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This invited lecture presents the most important achievements of theoretical and experimental studies which concerned dense magnetized plasmas and were performed in Poland during recent few years. Those studies were concentrated on high-current pulse discharges within the large mega-joule PF-1000 facility, which was operated at the IPPLM in Warsaw and investigated by researchers from the IPJ and IPPLM. The machine was operated mainly with a pure D2 filling, and the peak discharge current amounted to 1,5...1,8 MA. Theoretical studies concerned motions of accelerated primary deuterons and fusion-produced protons. Experimental investigations included a multi-frame laser interferometry, measurements of neutron yields, optical spectroscopy of plasma streams, diagnostics of fast electronand ion-streams, and measurements of an angular distribution of fusion protons.
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1562-6016 |
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Highlights of dense magnetized plasma research in Poland / M.J. Sadowski, M. Scholz // Вопросы атомной науки и техники. — 2010. — № 6. — С. 194-198. — Бібліогр.: 22 назв. — англ. |
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2025-11-26T10:29:47Z |
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| fulltext |
PLASMA DIAGNOSTICS
194 PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2010. 6.
Series: Plasma Physics (16), p. 194-198.
HIGHLIGHTS OF DENSE MAGNETIZED PLASMA RESEARCH
IN POLAND
M.J. Sadowski1,2, M. Scholz2
1 The Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk, Poland;
2 Institute of Plasma Physics and Laser Microfusion (IPPLM), 01-497 Warsaw, Poland
E-mail: msadowski@ipj.gov.pl
This invited lecture presents the most important achievements of theoretical and experimental studies which
concerned dense magnetized plasmas and were performed in Poland during recent few years. Those studies were
concentrated on high-current pulse discharges within the large mega-joule PF-1000 facility, which was operated at the
IPPLM in Warsaw and investigated by researchers from the IPJ and IPPLM. The machine was operated mainly with a
pure D2 filling, and the peak discharge current amounted to 1,5...1,8 MA. Theoretical studies concerned motions of
accelerated primary deuterons and fusion-produced protons. Experimental investigations included a multi-frame laser
interferometry, measurements of neutron yields, optical spectroscopy of plasma streams, diagnostics of fast electron-
and ion-streams, and measurements of an angular distribution of fusion protons.
PACS: 52.50.Dg; 52.58.Lq; 52.59.Hq; 52.65.Cc; 52.70.-m.
2. INTRODUCTION
Investigation of high-temperature plasmas in Poland,
which was initiated at IPJ about 55 years ago, has been
continued mainly within two institutes: IPJ and IPPLM
for many years [1]. This investigation included studies of
basic plasma physics and fusion-oriented research on
magnetic confinement fusion (MCF) as well as inertial
confinement fusion (ICF). The most important results of
these studies were presented at many international
conferences, including those held in Alushta [2-4].
The main aim of this lecture was to present highlights
of research on dense magnetized plasmas, which was
carried out in a frame of a close scientific collaboration of
IPJ and IPPLM teams after the previous Alushta-2008
conference. That research was concentrated on theoretical
and experimental studies connected with the large mega-
joule plasma focus PF-1000 facility, shown in Fig. 1.
Fig. 1. General view of PF-1000 experimental chamber
2. THEORETICAL STUDIES
In previous years theoretical analysis concerned mainly
the modeling of a current sheath dynamics using an
extended 2D-MHD model. It was shown that such an
approach describes the axial acceleration and radial
compression of the current sheath satisfactory [2]. In
particular the computed plasma density and electron
temperature distributions were reasonable and consistent
with other experimental results until the maximum
compression of the pinch column. An example of the
computation results is presented in Fig. 2.
Fig. 2. Plasma density distribution in PF-1000 during the
radial collapse phase , as computed by M. Scholz et al.
for t = 10 s after the discharge beginning [2]
In the next analysis attention was paid to modeling of
motions of the primary deuterons and fusion-produced
protons. As regards the accelerated primary particles,
computations for the uniform pinch showed that the fast
(>50 keV) deuterons (emitted at small angle to the z-axis)
should form a concentric image.
The next theoretical approach took into account that the
PF pinch column is never a uniform one and at the pinch
end there is usually formed a quasi-spherical region of
higher density plasma, as shown in Fig. 3.
Fig. 3. X-ray pinhole image showing the formation of
dense plasma at the end of the PF-1000 pinch column
The computer modeling of the deuteron emission,
which took into account influence of such dense plasma,
suggested that the deuteron angular distribution should
have a local minimum at the z-axis, as shown in Fig. 4.
-50.0 -40.0 -30.0 -20.0 -10.0 0.0 10.0 20.0 30.0
-30.0
-20.0
-10.0
0.0
10.0
20.0
30.0
5.0E+017 cm^-3
1.1E+019 cm^-3
2.1E+019 cm^-3
3.1E+019 cm^-3
4.1E+019 cm^-3
5.1E+019 cm^-3
Shot 5607
~8 cm
Electrode
mailto:msadowski@ipj.gov.pl
195
Fig. 4. Computed angular distribution of the deuterons
accelerated (to >50 keV in the PF-1000 experiment
That theoretical result was consistent with experimental
data collected within the PF-1000 experiments [2-4], but
there appeared another problem connected with a micro-
structure of the pinch column. In many Z-pinch and PF
experiments inside the pinch column there were observed
so-called current filaments. Strong local magnetic fields,
which surround such filaments, can modify motions of
charged particles considerably. Therefore, the recent
theoretical analyses were concentrated on studies of an
influence of the pinch micro-structure. Different models
of the pinch column were considered, as shown in Fig. 5.
Fig. 5. Various configurations of the pinch column and
current filaments, as considered for PF-1000 discharges
Detailed computations were performed particularly for
fast (about 3 MeV) fusion-protons [5-6]. It was shown
that their trajectories depend strongly on the configuration
of the current filaments [6-7], as presented in Fig. 6.
Fig. 6. Trajectories of fast fusion-produced protons, as
computed for different configurations of PF-1000 pinch
It should be noted that, due to local magnetic fields,
some fusion-protons could be emitted also in the upstream
direction. The described computer modeling of proton
trajectories enabled also an azimuthal distribution to be
calculated [6-7]. Detailed computations showed that the
azimuthal distribution of the fusion protons can have a
number of distinct peaks corresponding to the number of
the current filaments, as shown in Fig. 7.
Fig. 7. Azimuthal distribution of fusion-protons around
the PF-1000 axis, which was computed under
assumption of the appearance of 12 linear filaments
The results of the theoretical considerations could be
compared with results of experimental measurements, as
described below.
3. EXPERIMENTAL STUDIES
The recent experimental studies were concentrated first
of all detailed on measurements by means of a multi-
frame laser interferometer [8-9]. Due to the application of
a special splitter and interferometer arrangement, which
was designed by M. Paduch, it was possible to get 16
interferograms from a single PF-1000 shot. A quantitative
analysis of those inteferograms enabled the distributions
of isodensity lines and corresponding electron densities to
be determined [9], as shown in Fig. 8.
Fig. 8. Isodensity lines from interferograms and the electron
density distributions, as determined for
t=-30, 0 and 30 ns (in relation to the maximum compression)
The interferometric measurement delivered valuable
information about plasma dynamics and density
distributions during different phases of the PF pinch
formation and decay [8-9]. They informed also about
transformations of the PF-1000 pinch column structure
during the periods of the fusion-neutron emission [10].
- 1 0 0 - 8 0 - 6 0 - 4 0 - 2 0 0 2 0 4 0 6 0 8 0 1 0 0
- 2 0 0
0
2 0 0
4 0 0
6 0 0
8 0 0
1 0 0 0
1 2 0 0
1 4 0 0
1 6 0 0
1 8 0 0
angle
Homogeneous
column
Linear
filaments
Funnel-like
filaments
0 60 120 1 8 0 2 4 0 3 0 0 3 6 0
1 4
1 5
1 6
1 7
1 8
1 9
Fu
si
on
p
ro
to
n
ye
ld
[a
.u
.]
A z im u th a l a n g le [d e g ]
1 2 f ilam ents
196
Measurements of fusion-neutrons within the PF-1000
facility have in fact been carried out for many years [2-3].
In recent years there were carried out detailed time-
integrated and time-resolved measurements of fusion-
neutrons simultaneously with the laser interferometry
studies [10-14]. The time-integrated measurements of the
neutron yield were performed with a set of silver-
activation counters and scintillation detectors placed at
different distances from the PF-1000 pinch column, as
shown in Fig. 9.
Fig. 9. Arrangement of the activation and scintillation
detectors for neutron measurements at PF-1000
There were performed time-integrated measurements
with so-called “bubble chambers”. The measured total
neutron yields were compared with results of earlier PF
experiments performed in different labs. The best neutron
yield from PF-1000 shots carried out at 550 kJ, and the
maximum current equal to 1,95 MA, amounted to about
6 x 1011 neutrons. It was comparable with a result of a
large Los Alamos experiment LA3.
Some theoretical considerations suggested that the
neutron yield scaling should be proportional to I4, i.e. to
the fourth power of the current flowing through the pinch
column. In reality, all PF experiments performed so far
have demonstrated some saturation of the neutron yield
with an increase in the discharge current and energy
[1, 14]. That effect was the main motivation to perform
detailed studies of time-resolved the neutron pulses in
correlation with other signals, as presented in Fig. 10.
Fig. 10. Signals of X-rays, visible radiation (recorded
with a PIN diode), fast electrons, current derivative dI/dt
and fusion neutrons (measured at 1800) from PF-1000
at 734 kJ/33 kV and the peak current of 1.7 MA [1]
Recently attention was paid to the scaling of the total
neutron yield from PF-1000 versus the current flowing
through the pinch column during the maximum
compression. That current was measured by means of
miniature magnetic probes situated at different radii
(12 and 40 mm) at the anode end [14]. It was observed
that the total neutron yield is proportional to I4 measured
with the probe placed at r = 40 mm, as shown in Fig. 11.
Fig. 11. Neutron yield from PF-1000 as a function of the
pinch current, which was measured by means of
miniature magnetic probes [14]
During recent years particular attention was paid to
detailed time-resolved measurements of the neutron
signals [12-14]. An example of the time-resolved signals
from scintillation detectors is shown in Fig. 12.
Fig. 12. Signals from scintillation detectors placed at
1800 and at 00 to the discharge axis, both a distance
of 8 m from the pinch center
The first peaks were well correlated and showed X-ray
pulses, while the next peaks presented neutron-induced
peaks: the earlier peak (from 00) corresponded to
2.88 MeV neutrons, and the later one (from 1800)
corresponded to 2.14 MeV neutrons. The difference in
neutron energies, as obtained from the time-of-flight
measurements, showed that reacting deuterons could
move along the z-axis with velocities corresponding even
to about 120 keV.
Recently, particular efforts concerned measurements of
neutrons with very high temporal resolution, using new
scintillation probes BETA equipped with ultra-fast
scintillators and photomultipliers [14]. The new probes
showed a multi-peak structure of the recorded signals and
some shift in their maxima, as presented in Fig. 13.
Fig. 13. Comparison of X-ray and neutron signals from
the standard probe BRAVO (bright line) and a new ultra-
fast probe BETA (dark line), recorded for the same shot
0 1 2 3 4 5 6 7 8
- 8
- 7
- 6
- 5
- 4
- 3
- 2
- 1
0
vo
lta
ge
[V
]
t i m e [ µ s ]
197
Some PF-1000 discharges were also investigated by
means of the optical emission spectroscopy. A plasma
stream was observed during its free propagation, and
during its interactions with solid targets [15-16]. The use
was made of an optical Mechelle900 spectrometer,
which was situated as shown in Fig. 14.
Fig. 14. Experimental arrangement for optical
spectroscopy measurements within PF-1000
It was shown that one can determine experimental
conditions when a relatively pure deuterium plasma
stream arrives to the plane (z), as shown in Fig. 15.
Fig. 15. Changes of spectrum in the 450…700 nm range,
as recorded for different instants after the current
peculiarity, with the exposition equal to 0.1 µs
These measurements were of importance for studies of
targets made of materials to be used in fusion reactors,
e.g. tungsten [16]. Details of such studies are presented in
another paper at this conference [17].
Recent experimental efforts concerned also the
corpuscular diagnostics of fast electron- and ion-beams
emitted from the PF-1000 facility. To measure energy
spectra of electrons the use was made of a magnetic
analyzer equipped with a shielded X-ray film [18]. It was
shown that the electron beams, which are emitted from
deuterium discharges supplied from a 21…27 kV,
290…480 kJ condenser bank, have energies ranging up to
about 800 keV. To investigate the ion beams there were
applied small pinhole cameras equipped with shielded
PM-355 track detectors [19]. Mass- and energy-analysis
of the emitted ions was performed by means of a
miniature mass-spectrometer of the Thomson type [20]. It
was shown that for the experimental conditions described
above the emitted ion streams consist of many deuteron
micro-beams of energies ranging up to > 700 keV. It has
been confirmed by the first time-resolved measurements
of the deuteron beams. The appearance of such energetic
deuterons is explained as an effect of non-linear
phenomena occurring in a pinch column. Details of the
ion measurements are presented in another paper at this
conference [21].
Recently, particular attention has also been paid to
measurements of an angular distribution of fast fusion-
produced protons by means of pinhole cameras and
shielded PM-355 detectors [22], as shown in Fig. 16.
Fig. 16. Experimental arrangement for measurements of
angular distributions of the fusion-produced protons
The pinhole images of the fusion protons, which were
recorded at different azimuthal angles around the z-axis,
have shown considerable differences, as shown in Fig. 17.
Fig. 17. Examples of the scanned images of protons
recorded at different angles around the pinch axis
A quantitative analysis of the fusion-proton images (i.e.
the counting of the recorded tracks) made possible to
determine the azimuthal distribution, which demonstrated
a quasi-periodic character, as shown in Fig. 18.
Fig. 18. Total yields of fusion-protons, as recorded
around the PF-1000 z-axis during one experimental
campaign and fitted to the 12-peaks sinusoid
One can easily notice that the measured azimuthal
distribution of the fusion protons is consistent with
predictions of theoretical simulations performed for the
filamentary pinch column.
0 30 60 90 120 150 180 210 240 270 300 330 360
1
2
3
4
5
6
7
8
Fu
si
on
p
ro
to
ns
y
ie
ld
, a
.u
.
A z imu tha l ang le , deg .
450 500 550 600 650 700
0
5000
10000
15000
20000
Dα
C
u
I,I
I,I
II
C
u
I,I
I,I
II
15.0 to 15.1 µs
12.0 to 12.1 µs
7.0 to 7.1 µs
5.0 to 5.1 µs
3.0 to 3.1 µs
2.5 to 2.6 µs
Wavelength [nm]
In
te
ns
ity
[a
.u
.]
2.0 to 2.1 µs
2009.11.10, shots 8549-8555
z = 30 cm, t exp.= 0,1 us
without target
PF-1000
Uo= 25 kv, po =2,2 hPa
Dβ
x size, mm
y
si
ze
, m
m
0 4 8 12 16 20
20
16
12
8
4
0
counts, mm-2
0 250 500 750 1000 1250
Det. #5 - 85o
x size, mm
y
si
ze
, m
m
0 4 8 12 16 20
20
16
12
8
4
0
counts, mm-2
0 250 500 750 1000 1250
Det. #10 - 162o
198
SUMMARY AND CONCLUSION
The most important achievements of dense magnetized
plasma studies in Poland can be summarized as follows:
evident progress in theoretical analysis of PF discharges
(based on MHD and single-particle models); considerable
progress in experimental studies, and in particular the
mastering of a multi-frame laser interferometry, studies of
fast fusion-neutrons, applications of time-resolved optical
spectroscopy, measurements of ion- and electron-beams,
and measurements of fast fusion-protons.
It might be concluded that intense theoretical and
experimental studies of dense magnetized plasmas should
be continued in order to understand all physical
phenomena and to explain the experimental data.
REFERENCES
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2. M.J. Sadowski, M. Scholz // PAST. Series “Plasma
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3. M.J. Sadowski, et al.// PAST. Series „Plasma
Phys.“(12). 2006, N 6, p. 213-235.
4. M.J. Sadowski // PAST. Series „Plasma Phys.“(14).
2008, N 6, p. 90-94.
5. W. Stepniewski, et al. // Proc. Of SPPT-2008. Prague,
June 16-19, 2008/ CVUT, Prague 2008, p. 48.
6. M.J. Sadowski, et al. // Proc. of ICPIG-2009. Cancun,
July 12-17, 2009 / Univ. of Mexico, Mexico, 2009,
p. PA5-
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shop. Warsaw, Nov. 16-17, 2009/ IPPLM, Warsaw,
2009, p. Mo7.
8. M. Scholz, et al. // Proc. of ICDMP-2009 Workshop.
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p. Tu3.
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shop and Expert Meeting. Warsaw, Nov. 16-17,
2009/ IPPLM, Warsaw, 2009, CD issue.
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p. 05304.
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Phys.“(16). 2010, N 6, p. 199-201.
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Nancy, Nancy, 2010, p. P-58.
Article received 13.09.10
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