High-current low-energy electron beam generation in plasma system
Results of experimental investigations of low-energy high-current electron beam generation in a plasma-filled diode with a long plasma anode and an explosive emission cathode are given. An additional low-current electron beam was used to form the long plasma anode by means of the residual or prefi...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2006
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irk-123456789-792982015-03-31T03:02:19Z High-current low-energy electron beam generation in plasma system Agafonov, A.V. Bogachenkov, V.A. Krastelev, E.G. Ускорители заряженных частиц Results of experimental investigations of low-energy high-current electron beam generation in a plasma-filled diode with a long plasma anode and an explosive emission cathode are given. An additional low-current electron beam was used to form the long plasma anode by means of the residual or prefilled gas ionization. The long anode is used simultaneously as the transportation channel with predictable parameters of plasmas. Low-current additional beam is emitted from the thermionic cathode, which can have different geometric form. The solution developed provides to create radial profiled plasmas channels of desired plasmas density distribution with a high reproducibility. Приведены результаты экспериментов по генерации низкоэнергетического сильноточного электронного пучка в плазмонаполненном диоде с протяженным плазменным анодом. Для создания протяженного плазменного анода, одновременно представляющего собой и канал для транспортировки пучка, используется ионизация напущенного в систему газа вспомогательным слаботочным пучком электронов. Для генерации сильноточного пучка используются различные «взрывоэмиссионные» катоды. Создание плазмы вспомогательным электронным пучком, эмиттируемым с термокатода (энергия в сотни электронвольт при токе в единицы ампер), форма которого может варьироваться, позволяет формировать плазменные каналы с различным поперечным профилем с высокой воспроизводимостью. Наведено результати експериментів по генерації низькоенергетичного потужнострумового електронного пучка в плазмозаповненому діоді із протяжним плазмовим анодом. Для створення протяжного плазмового анода, що одночасно є каналом для транспортування пучка, використається іонізація напущеного в систему газу допоміжним слабкострумовим пучком електронів. Для генерації потужнострумового пучка використаються різні "вибухоемісійні" катоди. Створення плазми допоміжним електронним пучком, що емітується з термокатода (енергія в сотні електронвольт при струмі в одиниці амперів), форма якого може варіюватися, дозволяє формувати плазмові канали з різним поперечним профілем з високою відтворюваністю. 2006 Article High-current low-energy electron beam generation in plasma system / A.V. Agafonov, V.A. Bogachenkov, E.G. Krastelev // Вопросы атомной науки и техники. — 2006. — № 3. — С. 43-45. — Бібліогр.: 12 назв. —англ. 1562-6016 PACS: 29.27.-a http://dspace.nbuv.gov.ua/handle/123456789/79298 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
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English |
| topic |
Ускорители заряженных частиц Ускорители заряженных частиц |
| spellingShingle |
Ускорители заряженных частиц Ускорители заряженных частиц Agafonov, A.V. Bogachenkov, V.A. Krastelev, E.G. High-current low-energy electron beam generation in plasma system Вопросы атомной науки и техники |
| description |
Results of experimental investigations of low-energy high-current electron beam generation in a plasma-filled
diode with a long plasma anode and an explosive emission cathode are given. An additional low-current electron
beam was used to form the long plasma anode by means of the residual or prefilled gas ionization. The long anode is
used simultaneously as the transportation channel with predictable parameters of plasmas. Low-current additional
beam is emitted from the thermionic cathode, which can have different geometric form. The solution developed
provides to create radial profiled plasmas channels of desired plasmas density distribution with a high
reproducibility. |
| format |
Article |
| author |
Agafonov, A.V. Bogachenkov, V.A. Krastelev, E.G. |
| author_facet |
Agafonov, A.V. Bogachenkov, V.A. Krastelev, E.G. |
| author_sort |
Agafonov, A.V. |
| title |
High-current low-energy electron beam generation in plasma system |
| title_short |
High-current low-energy electron beam generation in plasma system |
| title_full |
High-current low-energy electron beam generation in plasma system |
| title_fullStr |
High-current low-energy electron beam generation in plasma system |
| title_full_unstemmed |
High-current low-energy electron beam generation in plasma system |
| title_sort |
high-current low-energy electron beam generation in plasma system |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2006 |
| topic_facet |
Ускорители заряженных частиц |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/79298 |
| citation_txt |
High-current low-energy electron beam generation in plasma system / A.V. Agafonov, V.A. Bogachenkov, E.G. Krastelev // Вопросы атомной науки и техники. — 2006. — № 3. — С. 43-45. — Бібліогр.: 12 назв. —англ. |
| series |
Вопросы атомной науки и техники |
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AT agafonovav highcurrentlowenergyelectronbeamgenerationinplasmasystem AT bogachenkovva highcurrentlowenergyelectronbeamgenerationinplasmasystem AT krasteleveg highcurrentlowenergyelectronbeamgenerationinplasmasystem |
| first_indexed |
2025-07-06T03:22:56Z |
| last_indexed |
2025-07-06T03:22:56Z |
| _version_ |
1836866262043459584 |
| fulltext |
HIGH-CURRENT LOW-ENERGY ELECTRON BEAM GENERATION
IN PLASMA SYSTEM
A.V. Agafonov1, V.A. Bogachenkov1, E.G. Krastelev2
1Lebedev Physical Institute, Leninsky pr. 53, V-333, Moscow, GSP-1, 119991, Russia
2Russian Research Centre “Kurchatov Institute”, Kurchatov Sq., Moscow, 123182, Russia
E-mail: agafonov@sci.lebedev.ru, krastelev@nfi.kiae.ru
Results of experimental investigations of low-energy high-current electron beam generation in a plasma-filled
diode with a long plasma anode and an explosive emission cathode are given. An additional low-current electron
beam was used to form the long plasma anode by means of the residual or prefilled gas ionization. The long anode is
used simultaneously as the transportation channel with predictable parameters of plasmas. Low-current additional
beam is emitted from the thermionic cathode, which can have different geometric form. The solution developed
provides to create radial profiled plasmas channels of desired plasmas density distribution with a high
reproducibility. Work supported by RFBR under grant 05-02-16442.
PACS: 29.27.-a
INTRODUCTION
Low-energy (of tens keV) high-current (of tens kA)
electron beams are applied for surface modification. For
these purposes plasma-filled diodes with explosive cath-
odes capable to generate high-current low-energy elec-
tron beams of microsecond duration with energy densi-
ties up to 10…40 J/cm2 were developed [1-12]. In a
plasma pre-filled diode an electron beam is generated in
a thin double-layer between a cathode and anode plas-
mas. This near-cathode layer is formed just after the be-
ginning of an accelerating voltage pulse and the voltage
applied is localized in this layer making possible the be-
ginning of the explosive emission from a cathode sur-
face.
To create a well defined plasma channel we use a
residual gas ionization by additional pulsed low-energy
(~300 eV), low-current (~(1…3) A) electron beam guid-
ed by a (200…300) G magnetic field. The main advan-
tages of this method are the high reproducibility and the
flexibility of an operative control of the plasma.
EXPERIMENTAL SETUP
A simplified diagram of the experimental setup is
shown in Fig.1.
Fig.1. Scheme of the setup: 1 – HV input cables;
2 - isolator; 3 – cathode of high-current diode; 4 - ther-
mocathode of low-current beam; 5 – plasma channel; 6
– collector; 7 – vacuum chamber
The high accelerating voltage from IK50-3 capaci-
tor bank (50 kV, 3 µF) charged to 10…40 kV is applied
to the diode via coaxial transmission cables, connected
to a cathode electrode supported by a high-voltage insu-
lator. At the other end of this electrode a flat graphite
cathode is installed. A plasma channel is formed by a
low-energy electron beam generated by a simple greed-
less electron gun (e-gun) with filament-type thermocath-
ode 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 to the grounded chamber. The biasing volt-
age pulse of 5…10 µs is applied prior to turning on the
pulsed power system of the main diode. A pulse pow-
ered (rise time is about 5 ms) one-layer solenoid is used
to produce the uniform guide field, typically of 200…
300 G.
Under 20 kV diode voltage the peak currents of
0.6 up to several kA with duration from 0.2 µs up to
0.8 µs of the electron beam downstream of e-gun was
recorded in preliminary experiments [11,12].
GENERATION OF HIGH-CURRENT BEAMS
IN THE DIODE WITH PLASMA ANODE
Plasma channel dynamics was observed using by
experimental measured dynamics of the impedance of
low-current thermocathode gun during the pulse of ac-
celerating voltage. The changing of the impedance un-
der condition of constant biasing voltage shows the
changing of effective cathode-anode gap and gives the
information about dynamics gas ionization for different
pressure. The measurements performed in a wide area
of parameters show that the beam current has changed
during the pulse.
The shape of the density profile of the plasma chan-
nel 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 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 or 0.5 mm diameter
tungsten wire. As it was seen from data obtained it cre-
____________________________________________________________
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2006. № 3.
Series: Nuclear Physics Investigations (47), p.43-45. 43
ated the plasma channel with a “flat top” and rather
sharp edges density profile.
Measurements were performed under the next condi-
tions. Plasma anode was created by 3-A (in both sides)
300 V auxiliary electron beam of 7 µs duration in the
external magnetic field of 300 G. Capacitor bank was
charged to the same voltage of 22 kV, the pressure of
residual gas was about (1…2)×10-3 Torr.
Fig.2 shows forms of the voltage and current pulses
of auxiliary gun with and without the cathode heating.
The division is 1 µs.
Fig.2. Voltages and currents pulses of the auxiliary
gun: 1 - total (6 A) emission current; 2 – current mea-
sured by the collector (3 A); 3 - voltage with 2×3 A
emission currents; 4 - voltage without emission of a
current (250 V)
The peak voltage on the gun with emission is 250 V
and rapidly decreases to about 80 V in saturated regime
due to internal resistance of the supply and resistance of
created plasma.
Fig.3 illustrates form of the pulses under condition
of turned off auxiliary gun. The division is 1 µs.
Fig.3. Accelerating voltage (curve 1) of 3.2 µs duration
with amplitude 22 kV, 1.8 µs time delayed collector cur-
rent with amplitude 90 A (curve 3) and signal of az-
imuths magnetic field (curve 2). Current measured Ro-
gowsky coil (curve 4)
A beam collector is moveable and may be replaced
by set of Langmuir probes to measure the plasma col-
umn parameters. Two resistive shunts and two Rogov-
sky 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, connect-
ed to the high-voltage collector located in oil, measures
the diode voltage. High-voltage pulse started just after
the finishing of the pulse voltage of auxiliary gun. Az-
imuthal magnetic field of the high-current beam was
measured additionally by screened solenoid coil placed
inside the vacuum chamber near the collector.
Fig.4 describes low-impedance plasma system on
the whole beginning since firing of high-voltage pulsed
supply. The division is 200 ns.
Fig.4. Accelerating voltage (curve 1) with amplitude
22 kV, beam current measured by the collector with am-
plitude 11.5 kA (curve 2), integrated signal of the az-
imuths magnetic field sender (curve 4), total current
measured Rogowsky coil (curve 3) at the input of high-
current diode
Maximum amplitude of high-current beam mea-
sured by the collector reaches 11.5 kA under the voltage
as higher as 18 kV. An integrated signal of the azimuths
magnetic field sender is observed simultaneously with a
collector signal. The total duration of the current pulse
is 1.6 µs and full duration at half maximum is about
400 ns. The time delay of the collector current relative
the beginning of the accelerating voltage reaches 80 ns
and corresponds to 16…18 kV level of the accelerating
voltage. It confirms the existence of a narrow accelerat-
ing gap near the cathode surface and the absence of
impedance collapse due to the presence of rather dense
plasma column. Maximum of current registered by Ro-
gowsky coil corresponds to the minimum of accelerat-
ing voltage on the diode and equals to about 8 kA.
CONCLUSION
These experiments have shown the possibility of
generation of high-current electron beams in low-
impedance plasma system even at accelerating voltage
as low as 20 kV. Peak current of 11.5 kA with duration
about 0.4 µs was recorded. The result ought to consider
as preliminary and it must be confirmed additionally by
independent measurements and analyses. First of all it is
necessary to observe bremsstrahlung signals simultane-
ously with beam current on collector to compare the du-
ration of both. Moreover, an energy spectrum and trans-
verse distribution of beam current are of importance
from the point of view of different applications.
To increase energy density of the beam up to neces-
sary values needed for surface modifications the accel-
erating voltage has to be increased up to 50…70 kV and
the duration of beam current has to be increased to 1 µs.
This task demands designing and construction a new ex-
perimental setup. Some more problems of generation of
curved plasma channel and generation of high-current
electron beam in a diode with curved anode must be tak-
ing into account in it.
44
REFERENCES
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ГЕНЕРАЦИЯ СИЛЬНОТОЧНОГО НИЗКОЭНЕРГЕТИЧЕСКОГО ЭЛЕКТРОННОГО ПУЧКА
В ПЛАЗМЕННОЙ СИСТЕМЕ
А.В. Агафонов, В.А. Богаченков, Е.Г. Крастелев
Приведены результаты экспериментов по генерации низкоэнергетического сильноточного электронного
пучка в плазмонаполненном диоде с протяженным плазменным анодом. Для создания протяженного
плазменного анода, одновременно представляющего собой и канал для транспортировки пучка,
используется ионизация напущенного в систему газа вспомогательным слаботочным пучком электронов.
Для генерации сильноточного пучка используются различные «взрывоэмиссионные» катоды. Создание
плазмы вспомогательным электронным пучком, эмиттируемым с термокатода (энергия в сотни
электронвольт при токе в единицы ампер), форма которого может варьироваться, позволяет формировать
плазменные каналы с различным поперечным профилем с высокой воспроизводимостью. Работа выполнена
при поддержке РФФИ по гранту 05-02-16442.
ГЕНЕРАЦІЯ ПОТУЖНОСТРУМОВОГО НИЗЬКОЕНЕРГЕТИЧНОГО ЕЛЕКТРОННОГО ПУЧКА
В ПЛАЗМОВІЙ СИСТЕМІ
А.В. Агафонов, В.А. Богаченков, Є.Г. Крастельов
Наведено результати експериментів по генерації низькоенергетичного потужнострумового електронного
пучка в плазмозаповненому діоді із протяжним плазмовим анодом. Для створення протяжного плазмового
анода, що одночасно є каналом для транспортування пучка, використається іонізація напущеного в систему
газу допоміжним слабкострумовим пучком електронів. Для генерації потужнострумового пучка
використаються різні "вибухоемісійні" катоди. Створення плазми допоміжним електронним пучком, що
емітується з термокатода (енергія в сотні електронвольт при струмі в одиниці амперів), форма якого може
варіюватися, дозволяє формувати плазмові канали з різним поперечним профілем з високою
відтворюваністю. Робота виконана за підтримкою РФФД по гранту 05-02-16442.
____________________________________________________________
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2006. № 3.
Series: Nuclear Physics Investigations (47), p.43-45. 45
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