Investigation of x-ray emission from high-current discharges of the PF type
The invited paper reports on measurements of soft x-rays emitted from hot plasmas produced in a modernised PF-1000U facility. The discharges were performed at the D2-filling with or without a Ne-admixture, under the initial pressure of 0.9 or 1.5 Torr and at the initial charging voltage equal to...
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| Zitieren: | Investigation of x-ray emission from high-current discharges of the PF type / E. Skladnik-Sadowska, M.J. Sadowski, K. Malinowski, W. Surala, D. Zaloga, M. Paduch, E. Zielinska, K. Tomaszewski // Вопросы атомной науки и техники. — 2016. — № 6. — С. 112-116. — Бібліогр.: 19 назв. — англ. |
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Skladnik-Sadowska, E. Sadowski, M.J. Malinowsk, K. Surala, W. Zaloga, D. Paduch, M. Zielinska, E. Tomaszewski, K. 2017-04-02T12:23:20Z 2017-04-02T12:23:20Z 2016 Investigation of x-ray emission from high-current discharges of the PF type / E. Skladnik-Sadowska, M.J. Sadowski, K. Malinowski, W. Surala, D. Zaloga, M. Paduch, E. Zielinska, K. Tomaszewski // Вопросы атомной науки и техники. — 2016. — № 6. — С. 112-116. — Бібліогр.: 19 назв. — англ. 1562-6016 PACS: 52.50.Dg; 52.58.Lq; 52.59.Hq; 52.70.-m; 52.70La https://nasplib.isofts.kiev.ua/handle/123456789/115330 The invited paper reports on measurements of soft x-rays emitted from hot plasmas produced in a modernised PF-1000U facility. The discharges were performed at the D2-filling with or without a Ne-admixture, under the initial pressure of 0.9 or 1.5 Torr and at the initial charging voltage equal to 16 or 18 kV. Time-integrated x-ray images were recorded with a pinhole camera situated side-on, at an angle of 75º to the z-axis. Differences in the pinch column structure were observed. Time-resolved measurements were performed with four PIN diodes located behind filtered pinholes. Two couples of PIN diodes (with Be-filters of 7 and 10 μm in thickness) observed 30 mm-diam. regions which had centres at a distance of 30 and 60 mm form the electrode outlets. From the recorded timeresolved x-ray signals the electron temperatures (Te) were calculated. For the pure D2-discharges the estimated Te values ranged from 75 to 250 eV depending on the discharge conditions. For discharges with a Ne-admixture Te values were higher and reached about 800 eV. Описаны измерения мягкого рентгеновского излучения горячей плазмы, генерируемой в модернизированной установке ПФ-1000U. Разряд происходит в вакуумной камере при напуске дейтерия D2 с добавкой Ne и без, начальное давление составляло 0,9 и 1,5 Торр, а рабочее напряжение 16…18 кВ. С помощью камеры обскура, расположенной под углом 75º относительно оси z, зарегистрированы рентгеновские снимки с временным разрешением. Наблюдается разница в структуре пинча. Измерения с временным разрешением проводились с помощью четырёх диодов, расположенных за отверстием с фильтром. Две пары диодов (с бериллиевым фильтром толщиной 7 и 10 мкм) передавали изображение из зон радиусом 30 мм, центры которых находятся на расстоянии 30 и 60 мм от среза электродов. Анализ сигналов рентгеновского излучения с временным разрешением позволил оценить электронную температуру (Те). Для разрядов с чистым дейтерием величина электронной температуры варьируется от 75 до 250 эВ в зависимости от условий разряда. Для разрядов с добавкой неона температура была выше и достигала 800 эВ. Описані вимірювання м’якого рентгенівського випромінювання гарячої плазми, що генерується в модернізованому пристрої ПФ-1000U. Розряд відбувається у вакуумній камері при напуску дейтерію D2 з домішкою Ne та без нього, початковий тиск складав 0,9 та 1,5 Торр, а робоча напруга 16…18 кВ. Рентгенівські знімки з часовим розділенням зареєстровані за допомогою камери обскура, яка знаходилась під кутом 750 відносно осі z. Спостерігається різниця в структурі пінча. Вимірювання з часовим розділенням проводились за допомогою чотирьох діодів, що розташовані за отвором із фільтром. Дві пари діодів (з берилієвим фільтром 7 та 10 мкм) передавали зображення із зон радіусом 30 мм в плазмі, центри діодів розташовано на відстані 30 та 60 мм від електродів. Аналіз сигналів рентгенівського випромінювання з часовим розділенням дозволив оцінити електронну температуру (Те). Для розрядів с чистим дейтерієм величина електронної температури змінюється від 75 до 250 еВ в залежності від умов розряду. Для розрядів з домішкою неону температура сягає 800 еВ. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Plasma dynamics and plasma-wall interaction Investigation of x-ray emission from high-current discharges of the PF type Исследование рентгеновского излучения сильноточных разрядов в установках типа ПФ Дослідження рентгенівського випромінювання сильнострумових розрядів у пристроях типу ПФ Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Investigation of x-ray emission from high-current discharges of the PF type |
| spellingShingle |
Investigation of x-ray emission from high-current discharges of the PF type Skladnik-Sadowska, E. Sadowski, M.J. Malinowsk, K. Surala, W. Zaloga, D. Paduch, M. Zielinska, E. Tomaszewski, K. Plasma dynamics and plasma-wall interaction |
| title_short |
Investigation of x-ray emission from high-current discharges of the PF type |
| title_full |
Investigation of x-ray emission from high-current discharges of the PF type |
| title_fullStr |
Investigation of x-ray emission from high-current discharges of the PF type |
| title_full_unstemmed |
Investigation of x-ray emission from high-current discharges of the PF type |
| title_sort |
investigation of x-ray emission from high-current discharges of the pf type |
| author |
Skladnik-Sadowska, E. Sadowski, M.J. Malinowsk, K. Surala, W. Zaloga, D. Paduch, M. Zielinska, E. Tomaszewski, K. |
| author_facet |
Skladnik-Sadowska, E. Sadowski, M.J. Malinowsk, K. Surala, W. Zaloga, D. Paduch, M. Zielinska, E. Tomaszewski, K. |
| topic |
Plasma dynamics and plasma-wall interaction |
| topic_facet |
Plasma dynamics and plasma-wall interaction |
| publishDate |
2016 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Исследование рентгеновского излучения сильноточных разрядов в установках типа ПФ Дослідження рентгенівського випромінювання сильнострумових розрядів у пристроях типу ПФ |
| description |
The invited paper reports on measurements of soft x-rays emitted from hot plasmas produced in a modernised
PF-1000U facility. The discharges were performed at the D2-filling with or without a Ne-admixture, under the initial
pressure of 0.9 or 1.5 Torr and at the initial charging voltage equal to 16 or 18 kV. Time-integrated x-ray images
were recorded with a pinhole camera situated side-on, at an angle of 75º to the z-axis. Differences in the pinch
column structure were observed. Time-resolved measurements were performed with four PIN diodes located behind
filtered pinholes. Two couples of PIN diodes (with Be-filters of 7 and 10 μm in thickness) observed 30 mm-diam.
regions which had centres at a distance of 30 and 60 mm form the electrode outlets. From the recorded timeresolved
x-ray signals the electron temperatures (Te) were calculated. For the pure D2-discharges the estimated Te
values ranged from 75 to 250 eV depending on the discharge conditions. For discharges with a Ne-admixture Te values were higher and reached about 800 eV.
Описаны измерения мягкого рентгеновского излучения горячей плазмы, генерируемой в модернизированной
установке ПФ-1000U. Разряд происходит в вакуумной камере при напуске дейтерия D2 с добавкой Ne и без, начальное
давление составляло 0,9 и 1,5 Торр, а рабочее напряжение 16…18 кВ. С помощью камеры обскура, расположенной
под углом 75º относительно оси z, зарегистрированы рентгеновские снимки с временным разрешением. Наблюдается
разница в структуре пинча. Измерения с временным разрешением проводились с помощью четырёх диодов,
расположенных за отверстием с фильтром. Две пары диодов (с бериллиевым фильтром толщиной 7 и 10 мкм)
передавали изображение из зон радиусом 30 мм, центры которых находятся на расстоянии 30 и 60 мм от среза
электродов. Анализ сигналов рентгеновского излучения с временным разрешением позволил оценить электронную
температуру (Те). Для разрядов с чистым дейтерием величина электронной температуры варьируется от 75 до 250 эВ в
зависимости от условий разряда. Для разрядов с добавкой неона температура была выше и достигала 800 эВ.
Описані вимірювання м’якого рентгенівського випромінювання гарячої плазми, що генерується в
модернізованому пристрої ПФ-1000U. Розряд відбувається у вакуумній камері при напуску дейтерію D2 з домішкою
Ne та без нього, початковий тиск складав 0,9 та 1,5 Торр, а робоча напруга 16…18 кВ. Рентгенівські знімки з
часовим розділенням зареєстровані за допомогою камери обскура, яка знаходилась під кутом 750
відносно осі z.
Спостерігається різниця в структурі пінча. Вимірювання з часовим розділенням проводились за допомогою чотирьох
діодів, що розташовані за отвором із фільтром. Дві пари діодів (з берилієвим фільтром 7 та 10 мкм) передавали
зображення із зон радіусом 30 мм в плазмі, центри діодів розташовано на відстані 30 та 60 мм від електродів. Аналіз
сигналів рентгенівського випромінювання з часовим розділенням дозволив оцінити електронну температуру (Те).
Для розрядів с чистим дейтерієм величина електронної температури змінюється від 75 до 250 еВ в залежності від
умов розряду. Для розрядів з домішкою неону температура сягає 800 еВ.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/115330 |
| citation_txt |
Investigation of x-ray emission from high-current discharges of the PF type / E. Skladnik-Sadowska, M.J. Sadowski, K. Malinowski, W. Surala, D. Zaloga, M. Paduch, E. Zielinska, K. Tomaszewski // Вопросы атомной науки и техники. — 2016. — № 6. — С. 112-116. — Бібліогр.: 19 назв. — англ. |
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PLASMA DYNAMICS AND PLASMA-WALL INTERACTION
ISSN 1562-6016. ВАНТ. 2016. №6(106)
112 PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2016, № 6. Series: Plasma Physics (22), p. 112-116.
INVESTIGATION OF X-RAY EMISSION FROM HIGH-CURRENT
DISCHARGES OF THE PF TYPE
E. Skladnik-Sadowska
1
, M.J. Sadowski
1-2
, K. Malinowski
1-2
, W. Surala
1
, D. Zaloga
1
,
M. Paduch
2
, E. Zielinska
2
, K. Tomaszewski
3
1
National Centre for Nuclear Research (NCBJ), Otwock-Swierk, Poland;
2
Institute of Plasma Physics and Laser Microfusion (IPPLM), Warsaw, Poland;
3
ACS Ltd., Warsaw, Poland
The invited paper reports on measurements of soft x-rays emitted from hot plasmas produced in a modernised
PF-1000U facility. The discharges were performed at the D2-filling with or without a Ne-admixture, under the initial
pressure of 0.9 or 1.5 Torr and at the initial charging voltage equal to 16 or 18 kV. Time-integrated x-ray images
were recorded with a pinhole camera situated side-on, at an angle of 75º to the z-axis. Differences in the pinch
column structure were observed. Time-resolved measurements were performed with four PIN diodes located behind
filtered pinholes. Two couples of PIN diodes (with Be-filters of 7 and 10 m in thickness) observed 30 mm-diam.
regions which had centres at a distance of 30 and 60 mm form the electrode outlets. From the recorded time-
resolved x-ray signals the electron temperatures (Te) were calculated. For the pure D2-discharges the estimated Te
values ranged from 75 to 250 eV depending on the discharge conditions. For discharges with a Ne-admixture Te
values were higher and reached about 800 eV.
PACS: 52.50.Dg; 52.58.Lq; 52.59.Hq; 52.70.-m; 52.70La
INTRODUCTION
Measurements of x-rays emitted from high-
temperature plasma supply valuable information about
its structure, composition and temperature [1-2]. Such
measurements were performed during extensive studies
of high-current pulse discharges within a modernised
PF-1000U facility, but they concerned mainly a
comparison of time-integrated x-ray pinhole images
recorded at different initial gas conditions [3]. More
detailed measurements of x-rays from discharges in PF-
1000U experiments, which were carried out with two
pinhole cameras, have been reported in another paper
[4]. In that study there were also performed preliminary
time-resolved measurements with filtered PIN diodes,
which observed different regions of the pinch column,
but the analysis of x-ray peaks concerned only their
correlations with current filaments and hot-posts
recorded on time-integrated x-ray images. Detailed
time-integrated x-ray measurements were performed
later and attention was focused on the observed micro-
structures (i.e., current filaments and hot-spots), but the
time-resolved x-ray signals were correlated with the
observed current filaments only [5]. Some time-
integrated x-ray measurements and analyses of fast
electron beams were carried out in another experiment,
but it was performed in a smaller PF-360U device [6].
More accurate x-ray measurements in the PF-1000U
facility and some estimates of the electron temperature
have been performed recently, but the use was made of
two PIN diodes only [7].
The main aim of this paper was to present results of
new detailed x-ray measurements carried out by means
of a filtered pinhole camera and four PIN diodes, which
were located behind pinhole collimators with different
filters. The first aim was to compare the time-integrated
x-ray images which could supply information about
differences in the internal structure of the pinch column.
The second aim was to analyse time-resolved x-ray
signals recorded behind different filters, and to estimate
values of the plasma electron temperature.
1. EXPERIMENTAL SET-UP
The reported experiments were carried out within the
modernised PF-1000U facility which was equipped with
460 mm long coaxial electrodes. The outer electrode
was composed of 12 stain-less steel tubes (each of
80 mm in diameter) which were distributed
symmetrically upon the 400 mm diam. cylindrical
surface. The inner electrode (anode) was a
230 mm diam. copper tube of closed by a copper plate
with a 50 mm diam. central hole. That hole contained a
fast-acing gas valve oriented along the z-axis.
Fig. 1. Cross-section of the PF-1000U chamber, which
shows positions of the diagnostic equipment
During the investigated discharges in the PF-1000U
device there were recorded voltage and current-
waveforms, as well as laser-interferometer images (with
a spatial resolution of 500 m) which were obtained
from a multi-frame Mach-Zehnder system equipped
with a Nd:YLF laser (generating 1-ns pulses, at
= 527 nm). Also recorded were hard x-ray and
neutron-signals from scintillation probes, as well as
neutron yields from silver-activation counters [8-10].
ISSN 1562-6016. ВАНТ. 2016. №6(106) 113
Other diagnostic tools were placed around the PF-
1000U chamber, as shown in Fig. 1.
In order to record time-integrated x-ray images the
use was made of two pinhole cameras equipped with
sensitive x-ray films. The first camera had a 1000 m
diaphragm and a 500 m thick Al-filter, while the
second camera had a 200 m diaphragm and a
10 m thick Be-filter. They were oriented at different
azimuthal angles, but the both cameras looked the PF
pinch column.
In order to obtain time-resolved x-ray signals from
the investigated PF-1000U discharges the use was
made of four PIN diodes of the Hamamatsu S9055 type,
which had active areas of 0.2 mm
in diameter and could
record photons < 1 keV. They were located behind four
separate 100 m diam. pinholes which were shielded by
different absorption filters. These PIN diodes, were
placed inside a small vacuum chamber pumped out by a
turbo-molecular pump [11]. A general view of a
fragment of the PF-1000U chamber with the installed
x-ray pinhole camera and the whole set of the PIN-
diodes is shown in Fig. 2.
Fig. 2. X-ray pinhole camera with a rotated film and the
PIN diodes system installed at the PF-1000U chamber
Due to the use of the separate collimators the PIN
diodes could detect x-rays from chosen parts of the
plasma pinch column. During the reported experiments
a 30 mm diam. viewing field of two PIN diodes,
equipped with different absorption beryllium (Be) filters
(of 7 and 10 m in thickness), was chosen on the z-axis,
with its centre at a distance of 30 mm from the electrode
ends. The second identical couple of the PIN diodes
observed another 30 mm diam. field, with the centre at a
distance of 60 mm from the electrodes, as shown in
Fig. 3.
According to tests of the applied Hamamatsu S9055
diodes, which were performed in the ACS Ltd.
Laboratory, the rise time of these detectors was about
100 ps, the fall time amounted to 220 ns, and the
FWHM was equal to about 300 ps [11]. Their temporal
responses did not depend considerably on the used
electronic cables.
It should be mentioned that the applied Be-filters of
different thickness were chosen in order to make it
possible to estimate electron temperature (Te) values of
plasma column emitting the observed x-radiation. For
this purpose the use was made of a dependence of the
x-ray intensity on the wavelength () and energy
(E = hc/) of the radiation, the Te value of the emitting
medium, and the absorption of the applied filters.
(characterised by their absorption coefficients j(E) and
thicknesses dj). This dependence is described by the
known formula
where the subscript j describes different filter materials
characterised by their absorption coefficients j(E) and
thicknesses dj [12].
Fig. 3. Viewing fields of the PIN diodes during the x-ray
measurements in the PF-1000U experiment
On the basis of the formula given above it was
possible to compute the ratio of the x-ray intensities
measured behind the chosen Be filters versus the
electron plasma temperature, as shown in Fig. 4.
0,1 1,0
1,0
2,0
2.4
2.2
1.8
1.6
1.4
1.2
1.20.80.60.40.2
Filters Be 1.3 & 1.85 mg/cm
2
I 1
.3
m
g
/c
m
2
/I
1
.8
5
m
g
/c
m
2
T
e
, keV
Fig. 4. Ratio of the x-ray intensities recorded behind
Be-filters of 7 m (1.3 mg/cm
2
) and 10 m
(1.85 mg/cm
2
) in thickness, as a function of the electron
temperature
It should, however, be noted that the described
measuring technique might be applied under specified
conditions only: 1. The absorption filters are made of
the same material (in this case Be); 2. The observed
plasma discharges do not contain many impurities; 3.
The Bremsstrahlung emission from plasma is
characterized by the Maxwellian distribution; 4. The
measured Te values are high enough to neglect an
influence of the recombination effects.
,
114 ISSN 1562-6016. ВАНТ. 2016. №6(106)
2. EXPERIMENTAL RESULTS AND
DISCUSSION
The reported recent series of experiments in the PF-
1000U facility was started by performing routine
diagnostic measurements. The preliminary discharges
were carried out at the pure D2-filling at the initial static
pressure of 0.9 or 1.5 Torr, and the initial charging
voltage of the condenser bank equal to 16 or 18 kV. The
discharge current waveforms and the current-derivative
(dI/dt) traces, as obtained from the Rogowski coil, were
correlated with signals from the scintillation probe
(recording hard x-ray and neutron pulses) as well as
with the time resolved signals from the PIN diodes
described above. An example of typical waveforms and
temporal correlations is presented in Fig. 5.
0 200 400 600
-6
-4
-2
0
2
4
6
-0.03
-0.02
-0.01
0.00
0.01
0.02
0.03
N
3
X
H3
Be 10 m, z = 6 cm
Be 7 m, z = 6 cm
Be 10 m, z = 3 cm
Be 7 m, z = 3 cm
PIN diodes
X
H2
N
2
N
1
P
IN
d
io
d
e
s
,
V
In
te
n
s
it
y
,
a
.u
.
t, ns
dI/dt #11268
X
H1
Scyntilator detector x100
Fig. 5. Signals obtained from the PF-1000U discharge
#11268. Current derivative waveform (dI/dt) is
correlated with hard x-ray (XH) and neutron pulses (N),
as well as with soft x-ray signals from two pairs of the
PIN diodes
From the presented example one can easily see that
the investigated discharge produced three hard x-ray
peaks and three distinct neutron pulses, which were
shifted in relation to the hard x-ray peaks by a time-of-
flight of neutrons to the scintillation detector (equal to
about 280 ns). The distinct soft x-ray signals were
emitted during the first hard x-ray emission only, and a
time shift between signals from the first pair of the PIN
diodes and those from the second pair of the detectors
was evidently caused by some delay of the emission of
from the second observation region in relation of that
from the first one.
An inteferometric image and a time-integrated x-ray
pinhole image, which were obtained for a typical for
PF-1000U discharge under static gas conditions, are
shown in Fig. 6.
In order to estimate the average electron temperature
(Te) values in the observed regions of the plasma
column, a more detailed analysis of the x-ray signals
from two pairs of the PIN diodes was performed. An
example of such an analysis is presented in Fig. 7.
From a comparison of the signals intensities an the
diagram shown in Fig. 4 it was estimated that in the
considered discharge the Te values in the first region
and the second one were equal to 180 and 100 eV,
respectively.
Fig. 6. Comparison of the image obtained with a laser
interferometer with that recorded with an x-ray pinhole
camera from a PF-1000U discharge # 11269. Two
circles show the observation fields of the PIN diodes
-0.05 0.00 0.05 0.10 0.15 0.20
-0.035
-0.030
-0.025
-0.020
-0.015
-0.010
-0.005
0.000
100 eV
P
IN
d
io
d
e
s
,
V
t, s
#11269
180 eV
Be 7 m, z = 6 cm
Be 10 m, z = 6 cm
Be 10 m, z = 3 cm
Be 7 m, z = 3 cm
Fig. 7. Time-resolved x-ray signals from two pairs of
the filtered PIN diodes, as recorded for the PF-1000U
discharge #11269 which was performed under the static
gas conditions, at p0 =2.0 hPa D2 and U0 = 18 kV
In subsequent experiments the discharges in the PF-
1000U facility were carried out at the dynamic gas
conditions, i.e., with the additional gas puffing of 1 cm
3
of pure deuterium, under the pressure of 0.1 MPa, at the
instant of about 2 ms before the main discharge
initiation. An example of the soft x-ray signals, which
were recorded at such conditions, is presented in Fig. 8.
From the signals presented in Fig. 8 one can easily
see that (in contrary to discharges at the static gas
conditions) the application of the additional gas puffing
caused a more complex structure of the x-ray emitting
regions. In addition to the first x-ray signals there were
emitted other short pulses (spikes). From a comparison
of the signals intensities from Fig. 8 and the diagram
shown in Fig. 4 it was estimated that in the considered
discharge the Te values in the first region (placed closer
to the electrode ends) were 210, 265 and 550 eV,
respectively. In the second (more distant) region the Te
values were evidently lower and they amounted to 115
and 110 eV only.
The observed x-ray spikes and a rise in Te value, as
observed with a time shift of 160…180 ns, might be
explained as a result of the formation of tiny plasma-
filaments and hot-spots, which can be characterized by
higher plasma densities and temperatures [2, 13-15].
ISSN 1562-6016. ВАНТ. 2016. №6(106) 115
0.0 0.1 0.2 0.3
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
550 eV
265 eV
110 eV
115 eV
P
IN
d
io
d
e
s
,
V
t, s
#11493
210 eV
Be 7 m, z = 6 cm
Be 10 m, z = 6 cm
Be 10 m, z = 3 cm
Be 7 m, z = 3 cm
Fig. 8. Time-resolved x-ray signals from two pairs of
the filtered PIN diodes, as recorded for the PF-1000U
discharge #11493 which was performed at p0 =1.2 hPa
D2 and U0 = 16 kV, but with the use of the additional
D2-puffing (about 2 ms before the main discharge)
The next series of discharges within the PF-1000U
facility was performed with the addition of a small neon
(Ne) admixture. From earlier studies [16-19] it was
known that at the application of a heavier gas there
appear distinct hot-spots. Such effects have also been
observed during the discharges investigated in the
described PF-1000U experiments, as shown in Fig. 9.
Fig. 9. Comparison of the time-integrated picture of the
visible radiation with that taken with an x-ray pinhole
camera for a PF-1000U discharge # 11501, which was
performed under the static filling at p0 = 1.2 hPa D2 +
1 % Ne2, GPD2 and U0 = 16 kV
The x-ray pinhole image presented in Fig. 9 has proved
that during the investigated PF-1000U discharge in the
viewing fields of the PIN diodes there were formed several
distinct hot-spots. These tiny plasma regions could have a
considerably higher density and temperature, what might
induce the emission of intense x-ray spikes. In order to
estimate the Te values for the considered discharge a
detailed analysis of the soft x-ray signals from the PIN
diodes was performed, as shown in Fig. 10. On the basis of
the x-ray signals presented in Fig. 10 and the diagram
shown in Fig. 4 it was estimated that in the considered
discharge the Te values in the first observation region were
equal to 315, 470, 830 and 740 eV, respectively. In the
second observation region, similarly to the discharges
without any admixture, the Te values were lower and they
amounted to 86, 135 and 105 eV only.
0.0 0.1 0.2 0.3
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
105 eV
135 eV
740 eV
830 eV
470 eV
85 eV
P
IN
d
io
d
e
s
,
V
t, s
#11501
315 eV
Be 7 m, z = 6 cm, x5
Be 10 m, z = 6 cm, x5
Be 10 m, z = 3 cm, x5
Be 7 m, z = 3 cm, x5
Fig. 10. Time-resolved x-ray signals from two pairs of
the filtered PIN diodes, as recorded for the PF-1000U
discharge #11501 performed with a small Ne admixture
It should here be noted that the highest values of Te
were obtained on the basis of distinct x-ray spikes,
which were probably emitted from the observed hot-
spots. This hypothesis has been confirmed by the fact
that the number of the recorded spikes corresponded to
the number of the distinct hot-spots. In fact, in the x-ray
pinhole image shown in Fig. 9 there were visible 3
distinct hot-spots in the first observation field, and 2
hot-spots in the second field. The corresponding
numbers of x-ray spikes were recorded upon the time-
resolved signals shown in Fig.10.
From an analysis of the x-ray signals presented in
Fig. 10 it might also be deduced that the considered hot-
spots (and the corresponding x-ray spikes) appeared
with some delays in relation to the main x-ray pulse,
which was well correlated with the dI/dt peak (see
above). From the waveforms presented in Fig. 10 it was
estimated that these delays ranged from about 100 ns to
about 130 ns in the first region, and from about 130 ns
to about 150 ns in the second region.
From the analysis of the considered x-ray spikes it
might also be deduced that the living time of the
individual hot-spots was of the order of the width of the
recorded x-ray spikes, i.e., it ranged from several ns to
about 10 ns.
SUMMARY AND CONCLUSIONS
The most important results of the studies described
above can be summarised as follows: 1. High-current
pulse discharges in the PF-1000U facility were carried
out under static initial gas conditions in pure deuterium,
at the dynamic conditions realised by the additional
puffing of deuterium, and at the application of a small
admixture of a Ne-gas; 2. The routine diagnostics
confirmed the results of the earlier experiments
performed in this facility, but particular attention paid to
time-resolved measurements of soft x-rays emitted from
two chosen regions of the plasma pinch column; 3. In
the discharges carried out at the static gas filling the x-
ray pulses were well correlated with the dI/dt peak, and
it was estimated that Te values in the 1
st
and the 2
nd
region were about 180 and 100 eV, respectively; 4. In
the discharges performed with the additional deuterium
puffing some plasma micro-regions of an increased x-
ray emission were observed near the electrode ends, and
the Te values were estimated to range from 210 to
550 eV in the 1
st
pinch region, and to about 110 eV in
the 2
nd
region; 5. During the PF-1000U discharges
5 cm
5 cm
116 ISSN 1562-6016. ВАНТ. 2016. №6(106)
carried out with a small admixture of a Ne-gas, in the
pinch column there were observed distinct plasma-
filaments and hot-spots, those emitted intense x-ray
spikes, and the estimated Te values in the hot-spots
formed near the electrode end ranged from about
300 eV to above 800 eV; 6. It was deduced that the
distinct hot-spots were formed with a delay of
100…150 ns in relation to the first main x-ray pulse
(corresponding to the pinch compression) and they
could exist from several to about 10 ns.
It might be concluded that the time-integrated and
time-resolved x-ray measurements supply valuable
information about the emission characteristics and
changes of the Te values in the observed pinch regions.
In order to collect more data such measurements should
be continued under different gas conditions. Particular
attention should be focused on studies of hot-spots,
because they are local sources of intense x-ray spikes
(induced probably by some higher-energy electron
beams), but they are possibly connected also with
sources of fast ion beams which play important role in
nuclear fusion reactions.
REFERENCES
1. Plasma Diagnostics / Edit W. Lochte-Holtgreven,
Amsterdam: “North-Holland Publishing Co”, 1968.
2. M.J. Sadowski and M. Scholz // Plasma Sources Sci.
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3. P. Kubes, M. Paduch, J. Cithardt, et al. // Phys.
Plasmas. 2014, v. 21, p. 082706.
4. W. Surała, M.J. Sadowski, M. Paduch, et al. //
Nukleonika. 2015, v. 60, p. 303-308.
5. M.J. Sadowski, M. Paduch, E. Składnik-Sadowska, et
al. //Plasma Sources Sci. Technol. 2015, v. 24, p. 055003.
6. W. Surala, M.J. Sadowski, R. Kwiatkowski, et al. //
Nukleonika. 2016, v. 61, p. 161-167.
7. E. Skladnik-Sadowska, D. Zaloga, M.J. Sadowski, et al.
// Plasma Phys. Control. Fusion. 2016, v. 58, p. 095003.
8. M. Scholz, L. Karpinski, M. Paduch, et al. // Czech. J.
Phys. 2000, v. 50, Suppl. 3, p. 179-184.
9. M. Scholz, R. Miklaszewski, M. Paduch, et al. //
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10.V.A. Gribkov, A. Banaszak, B.Bienkowska, et al. //
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Description. Warsaw: “ACS Ltd”. 2015.
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// NRL Report. 1969, № 6738, Washigton, DC, USA.
13. V.A. Gribkov, O.N. Krokhin, V.Ya. Nikulin, et al. //
ECA. 1998, v. 22, p. 2272-2275.
14. P. Kubes, M. Paduch, T. Pisarczyk, et al. // IEEE
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2014, v. 21, p. 072702.
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Letters 1984. v. 105A, p. 117-123.
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Article received 25.09.2016
ИССЛЕДОВАНИЕ РЕНТГЕНОВСКОГО ИЗЛУЧЕНИЯ СИЛЬНОТОЧНЫХ РАЗРЯДОВ
В УСТАНОВКАХ ТИПА ПФ
E. Skladnik-Sadowska, M.J. Sadowski, K. Malinowski, W. Surala, D. Zaloga, M. Paduch, E. Zielinska,
K. Tomaszewski
Описаны измерения мягкого рентгеновского излучения горячей плазмы, генерируемой в модернизированной
установке ПФ-1000U. Разряд происходит в вакуумной камере при напуске дейтерия D2 с добавкой Ne и без, начальное
давление составляло 0,9 и 1,5 Торр, а рабочее напряжение 16…18 кВ. С помощью камеры обскура, расположенной
под углом 75º относительно оси z, зарегистрированы рентгеновские снимки с временным разрешением. Наблюдается
разница в структуре пинча. Измерения с временным разрешением проводились с помощью четырёх диодов,
расположенных за отверстием с фильтром. Две пары диодов (с бериллиевым фильтром толщиной 7 и 10 мкм)
передавали изображение из зон радиусом 30 мм, центры которых находятся на расстоянии 30 и 60 мм от среза
электродов. Анализ сигналов рентгеновского излучения с временным разрешением позволил оценить электронную
температуру (Те). Для разрядов с чистым дейтерием величина электронной температуры варьируется от 75 до 250 эВ в
зависимости от условий разряда. Для разрядов с добавкой неона температура была выше и достигала 800 эВ.
ДОСЛІДЖЕННЯ РЕНТГЕНІВСЬКОГО ВИПРОМІНЮВАННЯ СИЛЬНОСТРУМОВИХ РОЗРЯДІВ
У ПРИСТРОЯХ ТИПУ ПФ
E. Skladnik-Sadowska, M.J. Sadowski, K. Malinowski, W. Surala, D. Zaloga, M. Paduch, E. Zielinska,
K. Tomaszewski
Описані вимірювання м’якого рентгенівського випромінювання гарячої плазми, що генерується в
модернізованому пристрої ПФ-1000U. Розряд відбувається у вакуумній камері при напуску дейтерію D2 з домішкою
Ne та без нього, початковий тиск складав 0,9 та 1,5 Торр, а робоча напруга 16…18 кВ. Рентгенівські знімки з
часовим розділенням зареєстровані за допомогою камери обскура, яка знаходилась під кутом 75
0
відносно осі z.
Спостерігається різниця в структурі пінча. Вимірювання з часовим розділенням проводились за допомогою чотирьох
діодів, що розташовані за отвором із фільтром. Дві пари діодів (з берилієвим фільтром 7 та 10 мкм) передавали
зображення із зон радіусом 30 мм в плазмі, центри діодів розташовано на відстані 30 та 60 мм від електродів. Аналіз
сигналів рентгенівського випромінювання з часовим розділенням дозволив оцінити електронну температуру (Те).
Для розрядів с чистим дейтерієм величина електронної температури змінюється від 75 до 250 еВ в залежності від
умов розряду. Для розрядів з домішкою неону температура сягає 800 еВ.
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