Experimental investigations of interaction of supercritical electron beams with plasma
The first section of the collective ions acceleration based on simultaneous temporal and spatial modulation of relativistic electron beam (REB) was studied experimentally. The virtual cathode was originated in the electrodynamic structure consisting of two tubes with different diameters (jump of ele...
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 2002 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2002
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Experimental investigations of interaction of supercritical electron beams with plasma / P.T. Chupikov, D.V. Medvedev, I.N. Onishchenko, B.D. Panasenko, Yu.V. Prokopenko, S.S. Pushkarev, R.J. Faehl, A.M. Yegorov // Вопросы атомной науки и техники. — 2002. — № 4. — С. 132-134. — Бібліогр.: 6 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859820572558491648 |
|---|---|
| author | Chupikov, P.T. Medvedev, D.V. Onishchenko, I.N. Panasenko, B.D. Prokopenko, Yu.V. Pushkarev, S.S. Faehl, R.J. Yegorov, A.M. |
| author_facet | Chupikov, P.T. Medvedev, D.V. Onishchenko, I.N. Panasenko, B.D. Prokopenko, Yu.V. Pushkarev, S.S. Faehl, R.J. Yegorov, A.M. |
| citation_txt | Experimental investigations of interaction of supercritical electron beams with plasma / P.T. Chupikov, D.V. Medvedev, I.N. Onishchenko, B.D. Panasenko, Yu.V. Prokopenko, S.S. Pushkarev, R.J. Faehl, A.M. Yegorov // Вопросы атомной науки и техники. — 2002. — № 4. — С. 132-134. — Бібліогр.: 6 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | The first section of the collective ions acceleration based on simultaneous temporal and spatial modulation of relativistic electron beam (REB) was studied experimentally. The virtual cathode was originated in the electrodynamic structure consisting of two tubes with different diameters (jump of electrodynamics) by REB, produced in magnetically insulated diode. At plasma assistance the low-frequency oscillations of REB current and the low-frequency microwave radiation were obtained due to the virtual cathode periodical relaxation in the processes of charge compensation by ionized residual gas.
|
| first_indexed | 2025-12-07T15:25:32Z |
| format | Article |
| fulltext |
PLASMA ELECTRONICS
132 Problems of Atomic Science and Technology. 2002. 4. Series: Plasma Physics (7). P. 132-134
EXPERIMENTAL INVESTIGATIONS OF INTERACTION OF
SUPERCRITICAL ELECTRON BEAMS WITH PLASMA
P.T. Chupikov, D.V. Medvedev, I.N. Onishchenko, B.D. Panasenko,
Yu.V. Prokopenko, S.S. Pushkarev, R.J. Faehl*, A.M. Yegorov
National Science Center " Kharkov Institute of Physics and Technology"
Academic St. 1, Kharkov, 61108, Ukraine, e-mail: onish@kipt.kharkov.ua
*Los Alamos National Laboratory, USA
The first section of the collective ions acceleration based on simultaneous temporal and spatial modulation of
relativistic electron beam (REB) was studied experimentally. The virtual cathode was originated in the electrodynamic
structure consisting of two tubes with different diameters (jump of electrodynamics) by REB, produced in magnetically
insulated diode. At plasma assistance the low-frequency oscillations of REB current and the low-frequency microwave
radiation were obtained due to the virtual cathode periodical relaxation in the processes of charge compensation by
ionized residual gas.
PACS: 52.40.Mj
1. INTRODUCTION
The structures with virtual cathode can be successful
applied in collective accelerators of charged particles [1,
2]. They are an integral part of two-section collective ion
accelerator based on simultaneous space and time
modulation of relativistic electron beam [3,4]. In such
accelerator the ions are accelerated by a field of space
charge slow wave generated by a temporally modulated
intensive electron flow, which is propagating in spatially
periodic structure. The mechanisms of the low frequency
excitation by ions moving in electron beams of the current
above the space charge limiting one were studied in [5,6].
This work is a part of efforts aimed researches of a
capability for creation of two-sectioned ion accelerator
[1]. The essence of approach for the solution of this
problem concludes to using of space charge fields in REB
for the acceleration of intense ion beams. In the base of
conception the collective ion acceleration by a
synchronous slow space charge wave, that originates from
simultaneous temporal and spatial modulation of REB.
The temporary modulation arises during relaxation of
virtual cathode at the plasma presence and spatial one is
caused by the spatially - periodic magnetic field.
The basis of this article is experimental researches of
the first section of collective ion accelerator. The
conditions of formation of a virtual cathode in cylindrical
electrodynamic structures are studied. The capability of
low frequency modulation of REB by charge
compensation of virtual cathode space charge by ionized
residual gas in system is realized.
2. EXPERIMENTAL SETUP
In the vacuum structures with supercritical electron
currents (above the space charge limiting current) a
virtual cathode (VC) should arise. The problem of our
research is to form VC in the anode tube (drift tube) of the
magnetically insulated diode. It was achieved by making
a jump of tube diameter. The arrangement for this
experiment was performed in the first section of two-
section collective ion accelerator [1]. The experimental
setup of it is represented in Fig. 1.
In Fig. 1 the structure of the high-current REB
accelerator is also shown. It is capable to generate the
electron beam with energy up to 300 keV and current up
to 4 kA at impulse duration of microsecond range. The
Marx generator (MG) total energy is equal 0.9 kJ when
each stage is charged by voltage of 30 kV.
The MG high-voltage pulse is applied to the
magnetically - insulated diode (1). The cylindrical
cathode was made from stainless steel. Its diameter was
31 mm and width of the emission edge was 0.1 mm.
The value of electron beam current is determined by
diameter of input cylindrical anode, the diameter of which
was equal 41, 46, and 50 mm and are provided with
follow-up used constructers in the injection region of the
beam. As it will be shown below the jump of
electrodynamic structure is necessary for the virtual
cathode formation. The inner diameter of the transport
electron cylindrical liner (drift tube) is equal 50 mm.
The electron beam is conveyed by a longitudinal
external magnetic field of the solenoid (2) with induction
up to 1.33 T. In the cathode region the value of magnetic
field was ~60 % from the value inside the solenoid. Such
configuration of magnetic field forms the electron beam
with diameter of 32 mm and wall thickness of 3 mm.
7
II-sectionI-section
VC
PG
2
1
5
5 3
4
5
MG
6
ASCS EMFF
Fig. 1. Collective accelerator of ions
MG – Marx generator; ASCS – accelerator starting and
control system; EMFF – external magnetic field
formation; VC – virtual cathode; PG – plasma gun.
mailto:onish@kipt.kharkov.ua
133
In Fig. 2 the cross-sectional portrait of electron beam
is shown in the collector region after REB transporting by
the homogeneous longitudinal magnetic field.
High-voltage dividers (resistive (3) and capacitive
(4)), magnetic sensors of currents (5) used on back
current-conductor (6) of MG and together with Faraday
cup which is as a current collector were used for the
control and the measurements of parameters of the high-
current electron accelerator. The periodic magnetic field
is formed by means of alternating aluminum and iron
rings (7), which was placed on the exterior of transport
electron beam liner. The radial thickness of aluminum
rings is equal 1 cm, and iron is 0.5 cm. The spatial period
formed by rings on the second section of ion acceleration
is equal 4 cm and the overall length of the structure has
the value of 4÷5 periods. The external periodic magnetic
field is necessary for ion acceleration in the second
section by slow space charge wave of modulated REB.
In Fig. 3 the oscillograms of the main parameters
of the high-current REB accelerator are shown. The peak
values of the oscillograms correspond to following
values: the input current of the magnetically - insulated
diode is 4.4 kA, and the collector REB current is 3.4 kA,
and diode voltage is 280 kV.
3.VIRTUAL CATHODE FORMATION
The conditions of virtual cathode formation in the
diode with magnetic insulation were studied using the
cylindrical electrodynamic structures. Structures of two
types: a circular tube of diameter 41 mm and waveguide
with jumping namely “diode anodic unit of diameter
41 mm - cylindrical drift liner of greater diameter 50 mm”
- were investigated experimentally.
In Fig. 4 the oscillograms of the diode input current
and the REB current on the collector (Faraday cup) are
shown. As it is seen from Fig. 4, a in the first case the
REB current injected from the cylindrical cathode is
transported without losses to the collector placed at the
end of the drift liner and in the homogeneous magnetic
field of induction 0.88 T. In the electrodynamic structure
with jumping the REB current on the collector is much
less than the diode input current and corresponds to value
of a space charge limiting vacuum current in the drift liner
(Fig. 4, b). It proves the possibility of the virtual cathode
formation in the structure with jumping.
4. PLASMA VIRCATOR
In case, when injected electron beam current exceeds
the value of space charge limiting vacuum current in the
given geometry, REB is locked in the drift liner under
operating of a sagging space charge potential. The
accumulated electrons form such potential distribution,
that it can be looks like a virtual cathode. In Fig. 5 the
oscillogram of input diode current (1) and the time
Fig. 3. Input (1), and collector (2) currents and diode
voltage (3)
Fig. 2. Portrait of electron beam
-500,0n 0,0 500,0n 1,0µ 1,5µ 2,0µ
-6
-5
-4
-3
-2
-1
0
2
1
C
ur
re
nt
, k
A
Time, s
a)
-500,0n 0,0 500,0n 1,0µ 1,5µ 2,0µ
-6
-5
-4
-3
-2
-1
0
2
1
Cu
rre
nt
, k
A
Time, s
b)
Fig. 4. Current oscillograms
1 – input diode current; 2 – collector current of REB
a) -tube diameter 41 mm; b) -jump of electrodynamic
structure from 41 mm to 50 mm
134
-500,0n 0,0 500,0n 1,0µ 1,5µ 2,0µ
-0,8
-0,6
-0,4
-0,2
0,0
0,2
V
ol
ta
ge
, V
Time, s
Fig. 6. Microwave radiation pulse
characteristic curve of the limiting vacuum current (2)
during accelerator operation pulse are shown. From the
Fig. 5 follows that in the transportation liner of electron
beam the VC should be formed at beginning of the pulse.
In the structure with supercritical electron beams the
oscillations of electrons between the cathode and virtual
cathode forms a power microwave radiation (so-called,
vircator-generator). In our case the frequency of these
oscillations has a value of several GHz. At plasma
assistance the low frequency modulation should take
place in the system with virtual cathode. As a result of
volume charge compensation the potential well disappears
in the system, and accelerated ions in the well escape the
region of virtual cathode. Thus, the system is returned in
the initial state and the process is repeated periodically.
As a result the high frequency oscillations of virtual
cathode become modulated. Besides the relaxing potential
well of virtual cathode modulates the REB current and
accelerates plasma ions up to energies determined by the
well depth.
In Fig. 6 the oscillogram of the detected microwave
radiation of vircator is shown. In our experiments the low
frequency modulation of plasma vircator microwave
radiation can be explained by charge compensation of
virtual cathode space charge by ionized residual gas at
pressure 2×10-4 Torr. The modulating frequency of
microwave radiation has value ~40 MHz. It is necessary
to notice, that the collector current of REB has the same
value of modulating frequency (Fig. 3).
5. CONCLUSION
In this paper, the first section of the collective ions
accelerator (Fig. 1) based on temporary and spatial
modulation of the dense relativistic electron beam was
experimentally investigated. The input current of the
magnetically - insulated diode was obtained 4.4 kA from
Marx generator with energy of 0.9 kJ. The transportation
of electron beam with pick current of about 4.4 kA was
realized along all drift liner with diameter of 41 mm. The
virtual cathode was formed in the electrodynamic
structure, which had the jumping of diameter from 41 mm
to 50 mm. High microwave radiation generated of the
virtual cathode was obtained.
In the condition of plasma assistance the low
frequency oscillation of electron beam and low frequency
microwave radiation were obtained by charge
compensation of virtual cathode space charge by ionized
residual gas. In the plasma vircator the plasma assistance
leads to virtual cathode disappearance due to
compensation its space charge by ions and to its
subsequent relaxation restoration at plasma
disappearance. Hence, there is an opportunity of low-
frequency modulation, determined by the ion time of
flight. This modulation is necessary to create the slow
wave space charge in the second section. The further
acceleration of ions will be occurred in a slow wave of a
temporary-modulated electron beam at its subsequent
spatial modulation by an external magnetic field.
The obtained research results confirms the possibility
to realize the idea of collective acceleration of ions by a
synchronous slow space charge wave generated by
simultaneous temporal and spatial modulation of REB.
This work was supported by STCU Project No.1569.
REFERENCES
[1] I.N. Onishchenko, S.S. Pushkarev Ion accelerator
based on plasma vircator // VANT. Issue: Nuclear-Physics
Investigations. 2001, V. 38, No.3, p. 41-43.
[2] W. Peter, R. J. Faehl, C. Snell et al Collective ion
acceleration by means of virtual cathodes // IEEE
Transactions on Nuclear Science. 1985, V. NS-32, No.5,
p. 3506-3508.
[3] V. A. Balakirev, A. M. Gorban, I. I. Magda et al
Collective acceleration of ions by modulated high-current
REB // Plasma Physics Reports. 1997, V. 23, No.4,
p. 323-327.
[4] V.V.Belikov, A.G.Lymar, and N.A.Khizhnyak. Ions
acceleration by modulated electron beam. // Pis’ma Zh.
Tekh. Fiz. 1975, Vol.1, No.13, p.615.
[5] V.A. Balakirev, I.N. Onishchenko, N.I. Onishchenko
LF oscillations excitation by the ion stream in high
current relativistic electron beams // Proc. of the 12th Int.
Conf. "Microwave and Telecommunication Technology".
(Sevastopol, Ukraine) September, 9-13, 2002, p. 373-374.
[6] P.I.Markov, I.N.Onishchenko, G.V.Sotnikov
Numerical simulation of processes in a supercritical
electron beam at the presence of plasma. //International
Conference and School on Plasma Physics and
Controlled Fusion. Alushta (Crimea), Ukraine, September
16-21 2002 : Book of Abstracts. P.145.
0,0 500,0n 1,0µ 1,5µ
-6
-4
-2
0
2
1
Cu
rr
en
t,
kA
Time, s
Fig. 5. Input diode current (1) and limited current (2) of
electron beam
|
| id | nasplib_isofts_kiev_ua-123456789-80298 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T15:25:32Z |
| publishDate | 2002 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Chupikov, P.T. Medvedev, D.V. Onishchenko, I.N. Panasenko, B.D. Prokopenko, Yu.V. Pushkarev, S.S. Faehl, R.J. Yegorov, A.M. 2015-04-14T17:19:32Z 2015-04-14T17:19:32Z 2002 Experimental investigations of interaction of supercritical electron beams with plasma / P.T. Chupikov, D.V. Medvedev, I.N. Onishchenko, B.D. Panasenko, Yu.V. Prokopenko, S.S. Pushkarev, R.J. Faehl, A.M. Yegorov // Вопросы атомной науки и техники. — 2002. — № 4. — С. 132-134. — Бібліогр.: 6 назв. — англ. 1562-6016 PACS: 52.40.Mj https://nasplib.isofts.kiev.ua/handle/123456789/80298 The first section of the collective ions acceleration based on simultaneous temporal and spatial modulation of relativistic electron beam (REB) was studied experimentally. The virtual cathode was originated in the electrodynamic structure consisting of two tubes with different diameters (jump of electrodynamics) by REB, produced in magnetically insulated diode. At plasma assistance the low-frequency oscillations of REB current and the low-frequency microwave radiation were obtained due to the virtual cathode periodical relaxation in the processes of charge compensation by ionized residual gas. This work was supported by STCU Project No.1569. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Plasma electronics Experimental investigations of interaction of supercritical electron beams with plasma Article published earlier |
| spellingShingle | Experimental investigations of interaction of supercritical electron beams with plasma Chupikov, P.T. Medvedev, D.V. Onishchenko, I.N. Panasenko, B.D. Prokopenko, Yu.V. Pushkarev, S.S. Faehl, R.J. Yegorov, A.M. Plasma electronics |
| title | Experimental investigations of interaction of supercritical electron beams with plasma |
| title_full | Experimental investigations of interaction of supercritical electron beams with plasma |
| title_fullStr | Experimental investigations of interaction of supercritical electron beams with plasma |
| title_full_unstemmed | Experimental investigations of interaction of supercritical electron beams with plasma |
| title_short | Experimental investigations of interaction of supercritical electron beams with plasma |
| title_sort | experimental investigations of interaction of supercritical electron beams with plasma |
| topic | Plasma electronics |
| topic_facet | Plasma electronics |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/80298 |
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