A study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction
Saved in:
| Published in: | Вопросы атомной науки и техники |
|---|---|
| Date: | 2001 |
| Main Authors: | , , , , , , , , |
| Format: | Article |
| Language: | English |
| Published: |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
|
| Online Access: | https://nasplib.isofts.kiev.ua/handle/123456789/79002 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Journal Title: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Cite this: | A study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction / N.I. Ajzatsky, A.N. Dovbnya, Eh.Yu. Khautiev, M.A. Krasnogolovets, V.I. Krauz, N.G. Reshetnyak, T.A. Semenets, Yu.Ya. Volkolupov, V.V. Zakutin // Вопросы атомной науки и техники. — 2001. — № 5. — С. 141-143. — Бібліогр.: 4 назв. — англ. |
Institution
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
nasplib_isofts_kiev_ua-123456789-79002 |
|---|---|
| record_format |
dspace |
| spelling |
Ajzatsky, N.I. Dovbnya, A.N. Khautiev, Eh.Yu. Krasnogolovets, M.A. Krauz, V.I. Reshetnyak, N.G. Semenets, T.A. Volkolupov, Yu.Ya. Zakutin, V.V. 2015-03-24T17:06:04Z 2015-03-24T17:06:04Z 2001 A study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction / N.I. Ajzatsky, A.N. Dovbnya, Eh.Yu. Khautiev, M.A. Krasnogolovets, V.I. Krauz, N.G. Reshetnyak, T.A. Semenets, Yu.Ya. Volkolupov, V.V. Zakutin // Вопросы атомной науки и техники. — 2001. — № 5. — С. 141-143. — Бібліогр.: 4 назв. — англ. 1562-6016 PACS numbers: 29.17.+w https://nasplib.isofts.kiev.ua/handle/123456789/79002 en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники A study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction Исследование эмиссионных характеристик плазменного фокуса в разрядной системе с металлокерамическим переходом Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
A study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction |
| spellingShingle |
A study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction Ajzatsky, N.I. Dovbnya, A.N. Khautiev, Eh.Yu. Krasnogolovets, M.A. Krauz, V.I. Reshetnyak, N.G. Semenets, T.A. Volkolupov, Yu.Ya. Zakutin, V.V. |
| title_short |
A study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction |
| title_full |
A study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction |
| title_fullStr |
A study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction |
| title_full_unstemmed |
A study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction |
| title_sort |
study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction |
| author |
Ajzatsky, N.I. Dovbnya, A.N. Khautiev, Eh.Yu. Krasnogolovets, M.A. Krauz, V.I. Reshetnyak, N.G. Semenets, T.A. Volkolupov, Yu.Ya. Zakutin, V.V. |
| author_facet |
Ajzatsky, N.I. Dovbnya, A.N. Khautiev, Eh.Yu. Krasnogolovets, M.A. Krauz, V.I. Reshetnyak, N.G. Semenets, T.A. Volkolupov, Yu.Ya. Zakutin, V.V. |
| publishDate |
2001 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Исследование эмиссионных характеристик плазменного фокуса в разрядной системе с металлокерамическим переходом |
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/79002 |
| citation_txt |
A study on emission characteristics of a plasma focus in the discharge system with a metal-ceramic junction / N.I. Ajzatsky, A.N. Dovbnya, Eh.Yu. Khautiev, M.A. Krasnogolovets, V.I. Krauz, N.G. Reshetnyak, T.A. Semenets, Yu.Ya. Volkolupov, V.V. Zakutin // Вопросы атомной науки и техники. — 2001. — № 5. — С. 141-143. — Бібліогр.: 4 назв. — англ. |
| work_keys_str_mv |
AT ajzatskyni astudyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT dovbnyaan astudyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT khautievehyu astudyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT krasnogolovetsma astudyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT krauzvi astudyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT reshetnyakng astudyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT semenetsta astudyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT volkolupovyuya astudyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT zakutinvv astudyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT ajzatskyni issledovanieémissionnyhharakteristikplazmennogofokusavrazrâdnoisistemesmetallokeramičeskimperehodom AT dovbnyaan issledovanieémissionnyhharakteristikplazmennogofokusavrazrâdnoisistemesmetallokeramičeskimperehodom AT khautievehyu issledovanieémissionnyhharakteristikplazmennogofokusavrazrâdnoisistemesmetallokeramičeskimperehodom AT krasnogolovetsma issledovanieémissionnyhharakteristikplazmennogofokusavrazrâdnoisistemesmetallokeramičeskimperehodom AT krauzvi issledovanieémissionnyhharakteristikplazmennogofokusavrazrâdnoisistemesmetallokeramičeskimperehodom AT reshetnyakng issledovanieémissionnyhharakteristikplazmennogofokusavrazrâdnoisistemesmetallokeramičeskimperehodom AT semenetsta issledovanieémissionnyhharakteristikplazmennogofokusavrazrâdnoisistemesmetallokeramičeskimperehodom AT volkolupovyuya issledovanieémissionnyhharakteristikplazmennogofokusavrazrâdnoisistemesmetallokeramičeskimperehodom AT zakutinvv issledovanieémissionnyhharakteristikplazmennogofokusavrazrâdnoisistemesmetallokeramičeskimperehodom AT ajzatskyni studyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT dovbnyaan studyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT khautievehyu studyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT krasnogolovetsma studyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT krauzvi studyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT reshetnyakng studyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT semenetsta studyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT volkolupovyuya studyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction AT zakutinvv studyonemissioncharacteristicsofaplasmafocusinthedischargesystemwithametalceramicjunction |
| first_indexed |
2025-11-25T23:32:41Z |
| last_indexed |
2025-11-25T23:32:41Z |
| _version_ |
1850583054478737408 |
| fulltext |
A STUDY ON EMISSION CHARACTERISTICS OF
A PLASMA FOCUS IN THE DISCHARGE SYSTEM WITH
A METAL-CERAMIC JUNCTION
N.I. Ajzatsky, A.N. Dovbnya, Eh.Yu. Khautiev1, M.A. Krasnogolovets2, V.I. Krauz1,
N.G. Reshetnyak, T.A. Semenets2, Yu.Ya. Volkolupov2, V.V. Zakutin
NSC KIPT, Kharkov, Ukraine
1 RSC, Kurchatov Institute, Moscow, Russia
2 KGTURE, Kharkov, Ukraine
PACS number: 29.17.+w
The high-current plasma-focus (PF) discharges are
known to be the source of intense neutron radiation and
X-rays in the quantum energy range from a few to hun-
dreds of kiloelectronvolts.
As demonstrated in numerous experimental papers,
with an increase of the power source energy above
W ~100 kJ, the known power scaling for the neutron
yield N~W2, established empirically for the PF systems,
is violated. This is mainly due to the fact that energy
current flowing in the plasma pinch on the axis of the
discharge system does not increase with W, and the part
of the discharge current starts to flow at the periphery
[1]. One of the factors preventing the overall current
flow in the pinch lies in repeated breakdowns in the in-
terelectrode gap [2] that shunt the principal current
channel and cause the emission PF parameters to de-
crease. The instability of high-current impulsing dis-
charges relative to repeated breakdowns is the funda-
mental property of these systems. The probability of re-
peated discharges grows with an increase in the energy
put into the discharge. Therefore, their suppression
presents a rather complicated problem. It has been es-
tablished [2, 3] that the place of repeated breakdown
formation is the insulator-inner electrode interface, be-
cause here a sharp electric-field gradient and a high spe-
cific heat release are concentrated.
To reduce the probability of repeated breakdowns of
the interelectrode gap, we have developed and investi-
gated a new design of the discharge system with a
smoothed potential gradient at the juncture of the insula-
tor and the inner electrode.
1 EXPERIMENTAL SETUP AND TECH-
NIQUES
The experiments were performed with the facility
KPF-1M schematically shown in Fig. 1 at a stored ener-
gy W ~40 kJ (V ~25 kV, T/2~7 µs).
The discharge system comprises the inner electrode
4, 50 mm in diameter, along the entire length of which
there is a through axial channel 5 ~14 mm in diameter;
the outer electrode made as a squirrel cage, 100 mm in
diameter, the electrodes, 200 mm in length. For compar-
ison of results, two separable insulators of the same size
and shape (each being a cylinder, 50 mm in diameter),
made of Alundum 2 (Al2O3) and Alundum 2 with a met-
al-ceramic junction 3 (MCJ) at one of the ends, were
used. The second insulator was produced by pressing
jointly the powders of aluminum oxide and molybde-
num so that the relative content of the metal varied from
0 to 100%. Correspondingly, the running conduction
over a length of 30 mm smoothly varies. In this case,
the electric field distribution gradient is smoothed off,
and the density of thermal energy flow decreases at the
initial part of the inner electrode due to the increased
thickness of the skin layer and its increased area of con-
tact on the current pick-off surface. The discharge sys-
tem is placed inside the vacuum chamber 6, which,
upon preevacuation to a pressure < 10-5 Torr, is filled
with the working gas to a pressure from 1 to 10 Torr.
Fig. 1. The schematic of the facility KPF-1M.
Experiments were made to take measurements of
voltage and discharge current, time and integral parame-
ters of X-ray/neutron radiation. The pictures of the dis-
charge were taken in the visible (moving-image camera)
and X-ray (pinhole camera) spectral regions. The energy
spectrum of ions accelerated in the PF was investigated
using the magnetic analyzer described in ref. [4]. Nucle-
ar photoemulsions were also used as a detector, provid-
ing the same energy resolution to determine the integral
ion distribution pattern.
2 EXPERIMENTAL RESULTS AND DIS-
CUSSION
The discharge dynamics and the PF formation were
investigated for two types of the insulator. The moving-
image camera photography of the discharge from both
the end and the side has shown that in the case of the in-
sulator with the MCJ, after the main plasma layer leaves
the insulator, there is no glow observed at the juncture
of the insulator and the inner electrode, whereas with
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №5.
Серия: Ядерно-физические исследования (39), с. 141-143.
141
the insulator without the MCJ the edge continues glow-
ing practically throughout the discharge. The absence of
a current flow at the above-mentioned juncture and of
the corresponding arrival of ionized vapors to the inter-
electrode gap considerably increases the electrical
strength of the initial part of the discharge volume.
Higher thermophysical characteristics of molybdenum-
base metal ceramics also positively contribute to a sig-
nificant decrease of surface erosion. In particular, no
sharp annular collar is formed, as is the case after sever-
al tens of discharges in the case of a usual insulator. It
has been demonstrated in ref. [3] that, as this collar is
formed at the juncture with the inner electrode, the re-
producibility of high-parameter discharges decreases.
From the comparison of current-voltage characteristics
(Figs. 2 a and b) it follows that in the case of the insula-
tor with the MCJ, the rise in the voltage at the moment
of PF formation is greater in the amplitude and duration.
Fig. 2. Tipical waveforms of voltage (upper) and cur-
rent (bottom) of the plasma focus discharge.
A deeper fall in the discharge current is observed,
this points to a more efficient dissipation of the magnet-
ic field energy.
At optimum conditions (W ~40 kJ, P ~6 Torr) the
average neutron yield with a good reproducibility in a
series of 60 discharges persists at a level of ~1010 neu-
trons/discharge. A great number of discharges is charac-
terized by the yield ~1.5⋅1010 neutrons/discharge, this
being comparable with the value that corresponds to the
scaling (N~W2) for the given energetics. For the Alun-
dum insulator without the MCJ the neutron yield is low-
er.
In the cases of using the insulator with the MC,
when the neutron yield is close to scaling, the spectra of
ion beams are of a discrete nature i.e., several bunches
of nearly monoenergetic ions are observed (Fig. 3).
The first (X1) and the second (X2) pulses correspond
to a hard X-ray radiation (HXR), and all the following
pulses correspond to the ion beams bunches with differ-
ent time-of-flight values. In the presence of the zero
point of time counts (moment of generation of the given
beam component in the PF) each of these oscillograms
can be considered, after some correction, as an energy
spectrum of accelerated ions. If one assumes that the ac-
celeration of ions and electrons occurs in the same elec-
tric fields, then the HXR pulse length ≤ 50 ns is the cri-
terion (pulse half-length is taken as a zero point), i.e.,
the time interval, within which the generation of all the
beam components observed in the oscillogram takes
place. The greater is the neutron yield, the higher is the
beam intensity. The generation of the ≥ 0.8 MeV ions is
practically always in synchronism with several great-
amplitude HXR surges.
Fig. 3. Pulses of ion beams.
The surges of intense HXR registered in the experi-
ment indicate that at a certain phase rather intense elec-
tron beams, along with ion beams, are formed in the PF.
In this series of experiments the entrance to the axial
channel in the inner electrode was closed by a ~15 mm
thick copper insert, so that the electrode end became
continuous. After 80 discharges a deep cavity, ~10 mm
in diameter, was formed at the anode end under the ac-
tion of the electron beam. The average energy of the
main portion of electrons in the beam was estimated by
the filter method to be between 30 and 60 keV.
The time-resolution registration of neutron radiation
and X-rays has shown that in the case of using the insu-
lator with the MCJ the discharges are mostly character-
ized by a multi-spike shape of pulses.
Fig. 4. Pulses from hard X-rays (X1 and X2) neutron ra-
diation (n1 and n2).
Figure 4 shows the oscillograms of signals from the
SNFT-3-type PMT with a scintillator detecting neutron
radiation (n1, n2), X rays (X1, X2) separated in the time-
of-flight R = 6.5.m, and also the discharge current
derivative (dI/dt). The neutron (X-ray) pulse length
ranges between 150 and 200 ns (40 to 50 ns) at half-
maximum.
3 CONCLUSION
Experiments with a new-design discharge system in-
cluding the MCJ between the anode and the insulator to
decrease the electric field gradients in the initial part of
142
the discharge volume were first made. The studies have
shown a significant improvement in the conditions for
the occurrence of the initial discharge phases. Parame-
ters of ion/electron beams generated in the PF have been
investigated. The ion beam is shown to consist of sepa-
rate, nearly monoenergetic bunches in the energy range
from 0.03 to 1 MeV.
REFERENCES
1. N.Openlander. Measurement of Magnetic Field and
Current Density Distribution in the Frascati 1 mJ
Plasma Focus Device // Com. Naz. Nucl. Center
Frascati Pap. 1978, N 6, p. 1-17.
2. V.I.Krauz. An experimental research of structures
in a plasma-focus discharge. A thesis abstract sub-
mitted for the degree of a Candidate of Physical-
Mathematical Sciences, Kharkov, 1988, p. 14 (in
Russian).
3. R.G.Salukvadze, S.P.Lalykin, Eh.Yu.Khautiev et
al. A device for plasma generation. Authorship Cer-
tificate N 1369658, MKI N 05 N 1/00, N 3935280.
Application 30.07.85.
4. V.I.Krauz, R.G.Salukvadze, Eh.Yu.Khautiev. Ener-
gy spectra of ion beams generated in the plasma fo-
cus // Fizika Plazmy. 1985, v. 11, is. 3, p. 281-287
(in Russian).
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №5.
Серия: Ядерно-физические исследования (39), с. 143-143.
143
|