Plasma diagnostics in the optical and X-ray regions on the plasma focus device PF-4 (installation Tyulpan)
The results of experiments received on the plasma focus (PF) device with energy stored equal 4 kJ are represented. Photos of the current plasma sheath (CPS), pre-pinch, sphere-like plasma formations are produced with the help of the electron-optical converter contained a gated micro-channel plat...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2006
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| Zitieren: | Plasma diagnostics in the optical and X-ray regions on the plasma focus device PF-4 (installation Tyulpan) / S.P. Eliseev, V.Ya. Nikulin, A.V. Oginov, A.A. Tikhomirov // Вопросы атомной науки и техники. — 2006. — № 6. — С. 147-149. — Бібліогр.: 8 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859616493670498304 |
|---|---|
| author | Eliseev, S.P. Nikulin, V.Ya. Oginov, A.V. Tikhomirov, A.A. |
| author_facet | Eliseev, S.P. Nikulin, V.Ya. Oginov, A.V. Tikhomirov, A.A. |
| citation_txt | Plasma diagnostics in the optical and X-ray regions on the plasma focus device PF-4 (installation Tyulpan) / S.P. Eliseev, V.Ya. Nikulin, A.V. Oginov, A.A. Tikhomirov // Вопросы атомной науки и техники. — 2006. — № 6. — С. 147-149. — Бібліогр.: 8 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | The results of experiments received on the plasma focus (PF) device with energy stored equal 4 kJ are represented.
Photos of the current plasma sheath (CPS), pre-pinch, sphere-like plasma formations are produced with the help of the
electron-optical converter contained a gated micro-channel plate (MCP) and the CCD-camera imaging system in the
visible region. The redial velocity of the CPS is about 10⁷ cm/s. Neon plasma electron density measured with the help of
the interferograms in the visible region and the spectrums in the soft X-ray region equals 3·10¹⁸ cm⁻³. Electron temperature
equals about 200 eV. Discharge integral photos were obtained with the help of the soft X-ray pinhole camera. Pictures with
2 μs resolution of the plasma luminescence above PF anode region were made by CCD-camera.
|
| first_indexed | 2025-11-28T21:36:34Z |
| format | Article |
| fulltext |
Problems of Atomic Science and Technology. 2006, 6. Series: Plasma Physics (12), p. 147-149 147
PLASMA DIAGNOSTICS IN THE OPTICAL AND X-RAY REGIONS
ON THE PLASMA FOCUS DEVICE PF-4 (INSTALLATION TYULPAN)
S.P. Eliseev, V.Ya. Nikulin, A.V. Oginov, A.A. Tikhomirov
P.N. Lebedev Physical Institute of RAS, Moscow, Russia
The results of experiments received on the plasma focus (PF) device with energy stored equal 4 kJ are represented.
Photos of the current plasma sheath (CPS), pre-pinch, sphere-like plasma formations are produced with the help of the
electron-optical converter contained a gated micro-channel plate (MCP) and the CCD-camera imaging system in the
visible region. The redial velocity of the CPS is about 107 cm/s. Neon plasma electron density measured with the help of
the interferograms in the visible region and the spectrums in the soft X-ray region equals 3·1018 cm-3. Electron temperature
equals about 200 eV. Discharge integral photos were obtained with the help of the soft X-ray pinhole camera. Pictures with
2 s resolution of the plasma luminescence above PF anode region were made by CCD-camera.
PACS: 52.58.Lq, 52.59.Hq, 52.70.-m
1. INTRODUCTION
The Dense Plasma Focus is a self-focusing high
current discharge in a rarefied gas. The CPS pushed by its
magnetic field is pressed to the camera axis producing
high-temperature dense plasma object. This plasma is a
different radiations source such as soft and hard X-ray,
neutron radiation, charged particles and radiation the
visible region. Therefore Plasma Focus is considered not
only as a source for the inertial confinement fusion (ICF)
with homogeneous irradiation of the X-ray [1], but also
for high density lithography [2, 3], X-ray microscopy,
radiography [4] and materials modification [5].
Investigations with such gas filling as neon, argon, heavy
hydrogen and their mixes are represented in this article.
Modification of the research parameters at gas puff and a
capacitor bank voltage changing was observed frequently.
In this paper, we intend to make the mechanism of the soft
X-ray generation more clearly. For this purpose was used
measurements with an imaging Bragg spectrometer, a high
speed imaging system at the base of electron-optical converter
with MCP in the visible region, the soft X-ray pinhole camera
and a laser shadowgraphy and interferometry.
2. APPARATUS
2.1. PLASMA FOCUS FACILITY
A Mather type plasma focus facility was used to generate a
current sheet for compressing filled high Z gases. The
discharge occurred between two single-axis electrodes. The
diameter of the inner (anode) and the outer (cathode) electrons
were 30 mm and 53 mm, respectively. Their lengths were 60
and 55 mm, respectively. The condenser bank consisted of
4x12 F, 25 kV capacitors. The facility operated at the bank
voltage from 8 to 14 kV and the total current did not exceed
0.4 MA at its maximum. Gas pressure in different experiments
was from 0.3 to 6 Torr.
Fig.1 shows the photo facility with different diagnostics,
Fig.2 is a Plasma Focus with moving current sheath view.
2.2. DIAGNOSTICS
A variety of diagnostics were employed to obtain
more detailed information about macroscopic behavior of
the CPS and plasma emission.
Electron-optical converter with MCP was used to obtain
photos of the CPS and plasma dynamics with high (3 ns)
temporal resolution. A digital camera NIKON-750 recorded
screen luminosity. The 200 m pin-hole was installed before
electron-optical converter to obtain clear spatial image.
Registration was produced under 90° to the vertical axis.
Fig.1. Photograph of the PF chamber with the different
diagnostics
Fig.2. Plasma Focus with moving current sheath view
Registration of the region over anode plane in the
visible region was carried out with the help of CCD-
camera with 2 s resolution.
Laser shadowgraphy and interferometry were based on a
single-pass Mach-Rozhdestvensky interferometer with the
varying arm of 1 – 2 m, an aperture of 10 cm and Nd:YAG-laser
at the second harmonics ( =1.06 m and 532 nm) with the pulse
of 120 mJ for 3 ns. The plasma light was removed by an aperture
placed at the focal point of the imaging lens and a glass filters
mounted just before the image sensor. CCD camera with aperture
of 6.5 x 4.8 mm size and 8.3 x 8.3 m pixel size recorded signal.
The dynamics and structure of the focused plasma can be
obtained with framing shadowgraphy, providing appropriate time
delay between the laser probing and plasma pinching instants.
An imaging Bragg spectrometer with convex mica
crystal was employed to analyze the soft X-ray emitted
from the pinched plasma. A mica (2d = 19.884 Å) convex
crystal with the diameter of 40 mm was employed in this
spectrometer. For the imaging, an entrance slit of 2.5 mm
in width and 19 mm in length was used. The spectrometer
was capable of collecting X-ray spectra in a 3 … 18 Å
region with the resolving power of R= > 500 and the
148
dispersion from 0.15 to 0.05 Å/mm. The angle between
the spectrum viewing direction and the plate axis was
about 45º. Closeness of the measured lines permitted to
avoid a spectral calibration of the spectrograph. For
removing background light and to additional crystal
defense from direct plasma flow 5 m Al foil filter was
arranged between an entrance slit and crystal. A
RAR2494 film was employed as a recording medium.
Discharge integral photos were obtained with the help
of the soft X-ray pinhole camera on the X-ray film of
RAR2494 type. The diameter of the pinhole was 230 m.
Beryllium foil filter (12 m of thickness with a pass band
< 20 Å) prevented from the visible light also emitted
from the source. Combination of the applied film and the
Be foil filter gave a registration region from 0.3 to 20 Å.
3. RESULTS AND DISCUSSION
3.1. DYNAMICS OF THE PLASMA
LUMINOSITY IN THE VISIBLE RIGION
By means of the electron-optical converter with built-in
MCP, photos of the plasma and current luminescence in a
visible range have been taken (Fig.3). Synchronization of the
moment MCP start was carried out by means of a signal from
the magnetic. The time synchronization was carried out in a
relation to the moment of the maximal current sheath
compression, which coincide with the feature moment on a
current derivative. The time exposition was about 3 ns.
In the photos obtained using neon as a filling gas, it is
visible, that at the time interval of –100 ns to –200 ns before
the maximal compression of the CPS when in a photo it is yet
visible, on an axis of the chamber already is available
obviously expressed pre-pinch. At the moments of time from -
10 up to +20 ns shining areas of the spherical form have been
found out. The luminescence of an evaporating metal from the
anode was seen through some microseconds after the maximal
CPS compression.
In the photos made by means of CCD camera with two
microseconds resolution (Fig.4) the vertical current column is
visible. In a different time moment the current shining zone
has various widths from 2 mm up to 2…3 cm. In some photos
similarity of twisting light layers is visible. It can be explained
by a twisting of current. In these experiments argon was used
as a feeling gas.
-100 ns -15 ns
+15 ns +2500 ns
Fig.3. EOC images of the discharge in the visible light at
the different instants
Fig.4. Images obtain by CCD camera with 2 s exposure
3.2. INTERFEROMETRY MEASUREMENTS
On Fig.5,d the shadow photo of compressed CPS which
made with use of the Nd: YAG-laser is represented.
Synchronization was carried out by the photo diode impulse what
arose during the moment of current sheath passage under it.
The plasma sheath during the compression phase on the
PF device generally has a good quasi-cylindrical axial
symmetry, hence only one perpendicular direction of laser
probing may be applied, and then the Abel integral equation
provides a good approximation. The obtained image is shown
in Fig.5,c). The interferential fringes are singled out and the
Fig.5. (a) Principal scheme of laser diagnostics and apparatus synchronization; (b) Profiles of electron density
obtained at different distances from anode surface. Samples of interferometric; (c) and shadow (d) images obtained
149
phase distribution is determined by the fringe shifts. The
calculation of the electron density profile is carried out using
numerical procedure of Abel inversion. The piecewise-
parabolic approximation of a refractive index profile with
variable piece lengths is employed to reduce paraxial error
growth. The error in the calculation was less than 10…20
percent. An example of data obtained is shown in Fig.5,b).
3.3. INTEGRAL PHOTOS AND SPECTRA IN
THE SOFT X-RAY REGION
Integral plasma shining in the soft X-ray region is shown in
Fig. 6. The photo has been made with the help of integral
pinhole camera. The height and width of the brightest pinched
plasma region were 4 and 1.5 mm, respectively. Recorded
radiation lies in a band from 0.3 up to 20 Å.
Spectrum and densitogram of neon plasma, which consist of
the resonance lines of the H-like and He-like ions and their
satellites in region 9…14 Å is shown on Fig. 6. The spectral
lines NeX 12.134 (H-like Lyman ), NeIX 13.447 (He-like
resonant line), NeIX 13.549 (He-like intercombinatory line),
"Member of Principal Series" (MPS) lines and a continuous
radiation were registered. Initial identification of the spectra was
produced using the H-like and He-like resonance lines.
Fig.6. Spectrum and densitogram of neon plasma, which
consists the resonance lines of the H-like and He-like ions
and their satellites
Consequent identification was carried out by means of the
following work [6]. The electron temperature was determined
using the ratio of the intensities H-like (line 1 on Fig.6) and it
satellite 19 (Te ~ 220 eV). The electron density was calculated
from the ratio of the intensities He-like resonance line 2 and
intercombinatory line 20 (Ne ~ 3·1018 cm-3) [7, 8].
Similar experiments were carried out with argon and its
mixes with heavy hydrogen as a filling gas. In spite of greater
features on the current derivative and significant output of
neutrons for the discharge in a mix (2·108 neutrons in 4 sr), in
the given experiments spectra were not observed. The most
probable explanation of this fact is that the temperature of the
compressed plasma is not high enough to excite H- and He-like
ions series of argon.
The particular advantage of used methods is simultaneous
measuring of the electron temperature and density by means of
the groups of the nearby lines the same elements that allowed to
attribute obtained values Ne and Te to the same area. Besides,
using gases with different charges of the nucleus will permit to
measure higher electron densities up to Ne ~ 1023 cm-3.
CONCLUSIONS
The dynamic behavior of the PF discharge in the visible
region was observed using shadow method on the base of the
Mach-Rozhdestvensky interferometer, photographing with the
help of the electron-optical converter and CCD-camera imaging
system. The existence of pre-pinch in the time range from –10
up to +20 ns relative to peculiarity on the current derivative was
demonstrated sphere-like shining.
Using the convex Bragg spectrometer, we obtained the
monochromatic images of the soft X-ray spectral lines for the
NeX Lyman series and for the NeIX series. In similar
experiments with argon and its mixes with heavy hydrogen
similar series is not revealed. Most probably, it is caused by
insufficient plasma temperature.
The electron temperature and density of the plasma hot spots
were estimated by several methods. Electronic temperature
~ 200 eV has been received from relative intensities of the
resonant lines and their satellites. Using relative intensity of
intercombinatory and resonance lines NeIX the electronic
density of plasma ~ 3·1018 cm-3 has been calculated. The same
result within experimental accuracy has been received by means
of interferometry measurements.
REFERENCES
1. R.J. Leeper et al. // Extended synopses 17th IAEA Fusion
Energy Conference, International Atomic Energy Agency,
IAEA-CN-69, 1998, p. 15.
2. J.S. Pearlman, J.C. Riordan // J. Vac. Sci. Technol. 1981,
v. 19, p. 1190.
3. I. Fomenkov. Performance of a dense plasma focus light
source for EUV lithography // 2nd Int. EUVL Symp. 2003.
4. S. Hussian, M. Shafig, R. Ahmad, A. Waheed, M. Zakaullah//
Plasma Sources, Sci. Technol. 2005, v. 14, p. 61-69.
5. L.I. Ivanov, A.E. Dedyurin, I.V.Borovitskaya, O.N. Krokhin,
V.Ya. Nikulin, S.N. Polukhin, A.A. Tikhomirov, A.S. Fedotov //
Pramana-J.Physics. Dec.2003, v. 61, 6, p. 1179.
6. R.L. Kelly// J. Phys. Chem. Ref. Data, 1987, v.16, 1.
7. L.P. Presnyakov // Uspekhi Fizicheskikh Nauk. May, 1976,
v.119, 1, p. 49-73 (in Russian).
8. L.A. Vainstain. Dielectronic recombination // Trudy FIAN,
v.119, p. 1-12 (in Russian).
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|
| id | nasplib_isofts_kiev_ua-123456789-82149 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-11-28T21:36:34Z |
| publishDate | 2006 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Eliseev, S.P. Nikulin, V.Ya. Oginov, A.V. Tikhomirov, A.A. 2015-05-25T15:52:54Z 2015-05-25T15:52:54Z 2006 Plasma diagnostics in the optical and X-ray regions on the plasma focus device PF-4 (installation Tyulpan) / S.P. Eliseev, V.Ya. Nikulin, A.V. Oginov, A.A. Tikhomirov // Вопросы атомной науки и техники. — 2006. — № 6. — С. 147-149. — Бібліогр.: 8 назв. — англ. 1562-6016 PACS: 52.58.Lq, 52.59.Hq, 52.70.-m https://nasplib.isofts.kiev.ua/handle/123456789/82149 The results of experiments received on the plasma focus (PF) device with energy stored equal 4 kJ are represented. Photos of the current plasma sheath (CPS), pre-pinch, sphere-like plasma formations are produced with the help of the electron-optical converter contained a gated micro-channel plate (MCP) and the CCD-camera imaging system in the visible region. The redial velocity of the CPS is about 10⁷ cm/s. Neon plasma electron density measured with the help of the interferograms in the visible region and the spectrums in the soft X-ray region equals 3·10¹⁸ cm⁻³. Electron temperature equals about 200 eV. Discharge integral photos were obtained with the help of the soft X-ray pinhole camera. Pictures with 2 μs resolution of the plasma luminescence above PF anode region were made by CCD-camera. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Plasma dynamics and plasma wall interaction Plasma diagnostics in the optical and X-ray regions on the plasma focus device PF-4 (installation Tyulpan) Article published earlier |
| spellingShingle | Plasma diagnostics in the optical and X-ray regions on the plasma focus device PF-4 (installation Tyulpan) Eliseev, S.P. Nikulin, V.Ya. Oginov, A.V. Tikhomirov, A.A. Plasma dynamics and plasma wall interaction |
| title | Plasma diagnostics in the optical and X-ray regions on the plasma focus device PF-4 (installation Tyulpan) |
| title_full | Plasma diagnostics in the optical and X-ray regions on the plasma focus device PF-4 (installation Tyulpan) |
| title_fullStr | Plasma diagnostics in the optical and X-ray regions on the plasma focus device PF-4 (installation Tyulpan) |
| title_full_unstemmed | Plasma diagnostics in the optical and X-ray regions on the plasma focus device PF-4 (installation Tyulpan) |
| title_short | Plasma diagnostics in the optical and X-ray regions on the plasma focus device PF-4 (installation Tyulpan) |
| title_sort | plasma diagnostics in the optical and x-ray regions on the plasma focus device pf-4 (installation tyulpan) |
| topic | Plasma dynamics and plasma wall interaction |
| topic_facet | Plasma dynamics and plasma wall interaction |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/82149 |
| work_keys_str_mv | AT eliseevsp plasmadiagnosticsintheopticalandxrayregionsontheplasmafocusdevicepf4installationtyulpan AT nikulinvya plasmadiagnosticsintheopticalandxrayregionsontheplasmafocusdevicepf4installationtyulpan AT oginovav plasmadiagnosticsintheopticalandxrayregionsontheplasmafocusdevicepf4installationtyulpan AT tikhomirovaa plasmadiagnosticsintheopticalandxrayregionsontheplasmafocusdevicepf4installationtyulpan |