Higt-current non-relativistic electron beam generation and transport
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| Veröffentlicht in: | Вопросы атомной науки и техники |
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| Datum: | 1999 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
1999
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| Zitieren: | Higt-current non-relativistic electron beam generation and transport / A.V. Agafonov, E.G. Krastelev, P.S. Mikhalev // Вопросы атомной науки и техники. — 1999. — № 3. — С. 60-61. — Бібліогр.: 4 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859517364594278400 |
|---|---|
| author | Agafonov, A.V. Krastelev, E.G. Mikhalev, P.S. |
| author_facet | Agafonov, A.V. Krastelev, E.G. Mikhalev, P.S. |
| citation_txt | Higt-current non-relativistic electron beam generation and transport / A.V. Agafonov, E.G. Krastelev, P.S. Mikhalev // Вопросы атомной науки и техники. — 1999. — № 3. — С. 60-61. — Бібліогр.: 4 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| first_indexed | 2025-11-25T20:47:28Z |
| format | Article |
| fulltext |
HIGH-CURRENT NON-RELATIVISTIC ELECTRON BEAM
GENERATION AND TRANSPORT
A.V.Agafonov, E.G.Krastelev, P.S.Mikhalev
P.N.Lebedev Physical Institute of RAS
INTRODUCTION
Low-energy (10-40 keV) high-current (1-20 kA)
electron beams are of great interest for researches on
material treatment, in particular, surface modification.
Earlier studies on surface modification were
concentrated on the application of high-power ion
beams. The situation was significantly changed with a
successful development of plasma-filled diodes with
explosive cathodes capable to generate high-current
low-energy electron beams of microsecond duration
with energy densities up to 10-40 J/cm2 [1, 2]. In a
plasma pre-filled diode an electron beam is generated in
a thin double-layer between a cathode and anode
plasmas. This near-cathode layer is formed just after the
beginning of an accelerating voltage pulse and the
voltage applied is localized in this layer making possible
the beginning of the explosive emission from a cathode
surface. Typically a set of arc-type plasma guns
installed at an anode ring-shape electrode is used as a
plasma source to fill the diode region and a beam drift
chamber [1-3]. The erosion sources have a number
disadvantages: parameters of plasmas are not well
reproducible, a powerful system for high-current arcs
ignition is needed, a plasma cloud is non-uniform and
fills a limited part of a drift chamber, etc. One known
solution of the problem is based on the anode and drift
chamber plasmas generation by a pulse reflective
(Penning) gas-discharge. It was developed and
successfully tested by authors of [3, 4]. We are
developing another a new approach to solve the
problems mentioned. It is based on the using of an
additional pulsed low-energy (~300 eV), low-current
(~1 A) electron beam guided by a 200-300 G magnetic
field to create a well defined plasma channel inside a
drift chamber and in a diode region by a residual or pre-
filled gas ionization. The main advantages of this
method are the high reproducibility and the flexibility of
an operative control of plasma parameters. The other
one is the generation of a well-limited in radial direction
plasma column with a well-defined position.
EXPERIMENTAL SETUP AND FIRST RESULTS
A test stand was designed and constructed for
initial experimental studies of performances of a new
plasma-filled diode and effects of the beam propagation.
A schematic diagram of the experimental setup is shown
in Fig.1.
Fig.1. Schematic diagram of the experimental setup.
The high accelerating voltage from IK50-3
capacitor bank (50 kV, 3 µF) charged to 10-40 kV is
applied to the diode via coaxial transmission cables (1),
connected to a cathode electrode supported by a high-
voltage insulator (2). At the other end of this electrode a
flat graphite cathode (3) is installed. A ring-shape anode
electrode (grounded diaphragm) is placed 2-4-cm
downstream from the cathode (not shown in Fig.1). A
plasma channel (5) is formed by low-energy electron
beam generated by a simple greed-less electron gun (e-
gun) with filament-type thermocathode (4) located
between two sections of the drift chamber. A
symmetrically propagating in a guiding magnetic field
2-way electron beam is produced using a pulse 250-
350 V, negative biasing of the hot tungsten wire with
respect of the grounded chamber. The biasing voltage
pulse (5 - 10 µs) is applied prior to turning on the pulsed
power system of the main diode. The wire heating
current is AC and is provided by a simple split
transformer. A pulse powered (rise time is about 5 ms)
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 1999. №3.
Серия: Ядерно-физические исследования. (34), с. 60-61.
60
one-layer solenoid (7) with additional compensating
coils near the e-gun flanges is used to produce the
uniform guide field, typically of 200-300 G. Shown in
Fig.1 a beam collector (6) is moveable and may be
replaced by set of Langmuir probes to measure the
plasma column parameters. Two resistive shunts and
two Rogovsky coils are used for the beam current
measurements at different positions – at high-voltage
insulator upstream of the diode, at the low-voltage e-
gun flange and at the end of the chamber. An outer
resistive divider, connected to the high-voltage collector
located in oil (8), measures the diode voltage.
Fig.2 shows the general view of the test stand
after replacement of the plastic insulator shown in Fig.1
by a new ceramic one (visible at the left side).
Fig.2. The test stand view.
At the first stage of the experiments parameters
of the plasma column generated by the low-voltage
beam were measured in a wide range of the
experimental conditions (residual gas pressure, biasing
voltage, tungsten thermocathode geometry, etc.) to find
out the optimal regimes for all components.
The channel plasma density was measured using
Langmuir probes with 1-cm long and 0,5-mm diameter
tungsten wire. During the measurements the probe wires
were oriented parallel or normal to the applied magnetic
field. Measurements were done at two positions of the
probes – near the diode region and 10-cm upstream
from the end of the drift chamber. The same data
obtained for both sets of probes showed that the plasma
column has approximately the same parameters from
both sides of e-gun. The peak ion densities derived from
the ion saturation current were about 1011 – 1012 cm-3 for
a probe bias of – 200 V and the pressure of a residual
gas of 0,1 - 1 mTorr. These data correspond to the
plasma channels exited by the e-gun with a zigzag-like
tungsten filament biased to –300V with respect to the
grounded wall of the vacuum chamber and for the total
emission current (measured in the filament biasing
circuit) approximately 1A. For given experimental
conditions the data of the measurements were well
reproducible – the variations from pulse to pulse were
well less than uncertainties of measurements.
The shape of the density profile of the plasma
channel depends on the geometry of the e-gun tungsten
wire and may be adjusted to the desired one by the
shaping of the thermocathode wire. During the
experiments the plasma column profile was measured
for different shapes of tungsten wires. For the first high-
current beam generation experiments it has been chosen
a zigzag-like flat thermocathode with a working area of
about 3-cm in diameter consisting of 7 zigzags of 0,3 or
0,5-mm diameter tungsten wire. As it was seen from
data obtained it created the plasma channel with a “flat
top” and rather sharp edges density profile. The optimal
shape of the wire will be found using the experimental
data on the high-current e-beam profile measurements
will have to be done during the next step of the
experiments.
First firings of the high-current diode were done
at 20 kV diode voltage. For an optimal time-delay
between e-gun biasing voltage pulse and the beginning
of the high-voltage pulse a peak current of 4,2 kA of the
electron beam downstream of e-gun was recorded.
REFERENCES
1. Ozur G.E. and Proskurovsky D.I., Pis’ma Zh. Tekh.
Fiz., v.14, n.5, p.413 (1988).
2. Nazarov D.S., Ozur G.E. and Proskurovsky D.I., Izv.
VUZOV: Fizika, 1994, n.3, p.100.
3. G.E.Ozur, D.I.Proskurovsky and D.S.Nazarov, In
Proc. Of the 11-th Int. Conf. BEAMS-96, Prague, Czech
Rep., v.1, p.359, 1996.
4. G.E.Ozur et al., Pis’ma Zh. Tekh. Fiz., v.23, n.10,
p.42. (1997).
61
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| id | nasplib_isofts_kiev_ua-123456789-81373 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-11-25T20:47:28Z |
| publishDate | 1999 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Agafonov, A.V. Krastelev, E.G. Mikhalev, P.S. 2015-05-14T20:56:28Z 2015-05-14T20:56:28Z 1999 Higt-current non-relativistic electron beam generation and transport / A.V. Agafonov, E.G. Krastelev, P.S. Mikhalev // Вопросы атомной науки и техники. — 1999. — № 3. — С. 60-61. — Бібліогр.: 4 назв. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/81373 en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Higt-current non-relativistic electron beam generation and transport Генерация и транспортировка сильноточного нерелятивистского электронного пучка Article published earlier |
| spellingShingle | Higt-current non-relativistic electron beam generation and transport Agafonov, A.V. Krastelev, E.G. Mikhalev, P.S. |
| title | Higt-current non-relativistic electron beam generation and transport |
| title_alt | Генерация и транспортировка сильноточного нерелятивистского электронного пучка |
| title_full | Higt-current non-relativistic electron beam generation and transport |
| title_fullStr | Higt-current non-relativistic electron beam generation and transport |
| title_full_unstemmed | Higt-current non-relativistic electron beam generation and transport |
| title_short | Higt-current non-relativistic electron beam generation and transport |
| title_sort | higt-current non-relativistic electron beam generation and transport |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/81373 |
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