Simulating multigun system with Langmuir law emission current
The results of numerical calculations of charged particle trajectories in a three-electrode structure are presented. A complex behavior is considered in the numerical calculations by the method of flow tubes of beams with a current limited by space charge. A method is given for choosing the relaxa...
Збережено в:
| Дата: | 2018 |
|---|---|
| Автор: | |
| Формат: | Стаття |
| Мова: | English |
| Опубліковано: |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2018
|
| Назва видання: | Вопросы атомной науки и техники |
| Теми: | |
| Онлайн доступ: | https://nasplib.isofts.kiev.ua/handle/123456789/147332 |
| Теги: |
Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Simulating multigun system with Langmuir law emission current / P.A. Martynenko // Вопросы атомной науки и техники. — 2018. — № 4. — С. 27-29. — Бібліогр.: 5 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
nasplib_isofts_kiev_ua-123456789-147332 |
|---|---|
| record_format |
dspace |
| spelling |
nasplib_isofts_kiev_ua-123456789-1473322025-02-09T09:56:41Z Simulating multigun system with Langmuir law emission current Чисельне моделювання багатоінжекторних систем з емісійним струмом, згідно закону Ленгмюра Численное моделирование многоинжекторных систем с током эмиссии, определяемым законом Ленгмюра Martynenko, P.A. Нерелятивистская электроника The results of numerical calculations of charged particle trajectories in a three-electrode structure are presented. A complex behavior is considered in the numerical calculations by the method of flow tubes of beams with a current limited by space charge. A method is given for choosing the relaxation parameter of the injector emission current at which after the completion of the transition process a stationary state is reached in the calculation. Робота присвячена дослідженню можливості розрахунку електронного та іонного інжекторів для системи, використаної в моделі колективного прискорювача. Наведено результати чисельних розрахунків траєкторій заряджених частинок у триелектродній структурі. Обговорюється складна поведінка при чисельних розрахунках пучків зі струмом, обмеженим просторовим зарядом, методом трубок струму. Наводиться спосіб вибору параметра релаксації емісійного струму інжектора, при якому після завершення перехідного процесу в розрахунку досягається стаціонарний стан пучка. Проведено порівняння результатів розрахунку з експериментальними даними як для сильнострумового інжектора електронів, так і для термоеміттера іонів лужних металів. Работа посвящена исследованию возможности расчета электронного и ионного инжекторов для системы, использованной в модели коллективного ускорителя. Приведены результаты численных расчетов траекторий заряженных частиц в трехэлектродной структуре. Обсуждается сложное поведение при численных расчетах пучков с током, ограниченным пространственным зарядом, методом трубок тока. Приводится способ выбора параметра релаксации тока эмиссии инжектора, при котором после завершения переходного процесса в расчете достигается стационарное состояние пучка. Проведено сравнение результатов расчета с экспериментальными данными как для сильноточного инжектора электронов, так и для термоэмиттера ионов щелочных металлов. 2018 Article Simulating multigun system with Langmuir law emission current / P.A. Martynenko // Вопросы атомной науки и техники. — 2018. — № 4. — С. 27-29. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS: 29.25.Ni https://nasplib.isofts.kiev.ua/handle/123456789/147332 en Вопросы атомной науки и техники application/pdf Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| topic |
Нерелятивистская электроника Нерелятивистская электроника |
| spellingShingle |
Нерелятивистская электроника Нерелятивистская электроника Martynenko, P.A. Simulating multigun system with Langmuir law emission current Вопросы атомной науки и техники |
| description |
The results of numerical calculations of charged particle trajectories in a three-electrode structure are presented.
A complex behavior is considered in the numerical calculations by the method of flow tubes of beams with a current
limited by space charge. A method is given for choosing the relaxation parameter of the injector emission current at
which after the completion of the transition process a stationary state is reached in the calculation. |
| format |
Article |
| author |
Martynenko, P.A. |
| author_facet |
Martynenko, P.A. |
| author_sort |
Martynenko, P.A. |
| title |
Simulating multigun system with Langmuir law emission current |
| title_short |
Simulating multigun system with Langmuir law emission current |
| title_full |
Simulating multigun system with Langmuir law emission current |
| title_fullStr |
Simulating multigun system with Langmuir law emission current |
| title_full_unstemmed |
Simulating multigun system with Langmuir law emission current |
| title_sort |
simulating multigun system with langmuir law emission current |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2018 |
| topic_facet |
Нерелятивистская электроника |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/147332 |
| citation_txt |
Simulating multigun system with Langmuir law emission current / P.A. Martynenko // Вопросы атомной науки и техники. — 2018. — № 4. — С. 27-29. — Бібліогр.: 5 назв. — англ. |
| series |
Вопросы атомной науки и техники |
| work_keys_str_mv |
AT martynenkopa simulatingmultigunsystemwithlangmuirlawemissioncurrent AT martynenkopa čiselʹnemodelûvannâbagatoínžektornihsistemzemísíjnimstrumomzgídnozakonulengmûra AT martynenkopa čislennoemodelirovaniemnogoinžektornyhsistemstokomémissiiopredelâemymzakonomlengmûra |
| first_indexed |
2025-11-25T14:36:26Z |
| last_indexed |
2025-11-25T14:36:26Z |
| _version_ |
1849773405874683904 |
| fulltext |
ISSN 1562-6016. ВАНТ. 2018. №4(116) 27
SIMULATING MULTIGUN SYSTEM WITH LANGMUIR LAW
EMISSION CURRENT
P.A. Martynenko
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
E-mail: martynenkopetr91@gmail.com
The results of numerical calculations of charged particle trajectories in a three-electrode structure are presented.
A complex behavior is considered in the numerical calculations by the method of flow tubes of beams with a current
limited by space charge. A method is given for choosing the relaxation parameter of the injector emission current at
which after the completion of the transition process a stationary state is reached in the calculation.
PACS: 29.25.Ni
INTRODUCTION
This paper is devoted to the study of the possibilities
of calculating the self-consistent state of the electron
and heavy-ion beam for the system used in the collec-
tive accelerator model [1, 2]. There are injectors of a
primary electron beam and a secondary heavy-ion beam
with thermionic cathodes (Fig. 1). The system sizes are
selected to equal the experimental sizes. The final goal
is to obtain the heavy-ion beam passage into the anode
of a high perveance electron gun with a cathode and
anode apertures.
EL and ION program was created for this axial elec-
trode electro-optical system simulation. There is a prob-
lem in calculating the trajectories of ions and electrons,
which begin to move from the emission surface of the
electron and ion guns with zero velocities. In this case,
the emission current is determined by the “3/2 power”
Langmuir law and the initial conditions for the trajecto-
ries correspond to the regime of current limitation by
space charge (see the formulas in the attachment). The
program implements the flow tube method for calcula-
tion and does not require such multiple particles and
such multiple potential distribution calculation as in PIC
methods. The final goal of the program is to calculate
the self-consistent state of some beams.
First of all it is necessary to obtain an answer to the
question whether the electron beam self-consistent state
to obtaine in the presence of heavy-ion beam will be
stationary. Since for one electron beam simulation the
perveance value depends on the transition process for
the different relaxation parameter values (Fig. 2). This
result is called complex behavior [3] and will be dis-
cussed further (see COMPLEX BEHAVIOUR). It is
suggested that for electron beam current over ion beam
current the electron beam self-consistent state remain
constant. Because of this only heavy-ion beam injection
whithout ion charge effects will be discussed further
(see HEAVY-ION BEAM SIMULATION).
The second question is about the use of thermionic
cathode. In the model of the collective ion accelerator
by a modulated electron beam in the goffered conduct-
ing screen was used ion gun with heavy ions like K+
with a special charge state 1+. However, in the ad-
vanced acceleration techniques different multiply
charged ions like nitrogen, carbon and others from
plasma gun need to be transport [4].
COMPLEX BEHAVIOUR
The first of all, the method of successive step by step
approximations for the electromagnetic field and the
charge flow trajectory calculation was used as it can
been seen in Fig. 1. This is only one electron beam sim-
ulation.
The algorithm that simulates the transition process
the system uses to establish a self-consistent state of the
flow method relaxation of emission current injected into
the system. Given a emission current determined by the
conditions at the cathode, determined the trajectory of
the particles and the distribution of the charge density in
the space corresponding to the found particle trajecto-
ries. Given the distribution of the charge density deter-
mined the potential distribution. Repeating this se-
quence at each step examined the transition process in
the system [5]. Fig. 2 contains the 19 consecutive mi-
croperveance values for different values of the emission
current relaxation parameter for high microperveance
electron gun (see Fig. 1). What is noticed for different
values of relaxation parameter: 1) it is seen that for val-
ues of the relaxation parameter less than 0.7 microp-
erveance values converge to a value of near 3 2) if val-
ues of the relaxation parameter over than 0.7 microp-
erveance diverge. It may be as a stationary and periodic
or chaotic state of dynamic system in the given external
stationary electric field for different values of the pa-
rameter [3]. It is easy to explain this behavior.
The determination of the emission current at the first
step for the vacuum distribution of the potential in the
diode leads to an excessively high value of the emitted
current. The value of the space charge at the first step
will be greater with this definition than in the stationary
state. Therefore, the potential distribution determined at
the second step differs from the stationary one. Because
of this, the field near the surface of the cathode can
change the sign for some tubes of current. And further,
if the field on the cathode prohibits the emission current,
then the emitted current will decrease and the distribu-
tion of the space charge will change. Therefore, the po-
tential distribution determined at the next step differs
from the previous one. Next, the dynamics will be re-
peated, which leads to a step-by-step oscillation of the
current (microperveance) and space charge values. But
as follows from the theory, the equality of the field at
the cathode to zero is an equilibrium condition (see at-
tachment) for the existence of a certain diode current
and potential distribution, at which the equilibrium dis-
tribution of the space charge is ensured.
ISSN 1562-6016. ВАНТ. 2018. №4(116) 28
Fig. 1. (up) − High perveance electron gun;
(middle) − Axes potential distribution; (down) − Ion gun
A method for choosing a the emission current relaxation
parameter has been developed, in which, in the first step,
the current relaxation parameter of each tube is several
times smaller than for the subsequent steps. The value
of the initial relaxation parameter determines the initial
value of the current density for each tube at which this
value is close to the value in the stationary state. The
value of the current relaxation parameter at subsequent
steps determines the dynamics of the system step by
step. For a parameter value that is less than the critical
value during the transient process, the microperveance
oscillation range decreases, and at the parameter values
greater than the critical value increases, as explained
above.
Fig. 2. Microperveance values for some relaxation
parameter (gama) values
HEAVY-ION BEAM SIMULATION
An ion source to be used in collective method accel-
eration experiments has been designed, constructed and
tested. Fig. 1 (down) shows the injection of the heavy-
ion beam in more detail. In this region, the particle tra-
jectories are calculated with smaller step sizes and pri-
mary externally electron beam are accelerated down-
stream as it can been seen in Fig. 1 (up). These parame-
ters optimised in previous simulations to obtain a parti-
cle trajectory accuracy better than 0.5%, important to
model the heavy-ion gun It seems that there is a focus-
ing in the trajectories of the heavy-ion beam better then
in case simulating an ion beam without an electron
beam.
The results of the calculation are compared with the
experimental data for both the high-current electron
injector and for the thermoemitter of alkali metal ions.
ATTACHMENT
When a voltage is applied to the diode gap, electrons
emitted by a heated cathode form a space charge distri-
bution in the diode gap in a time of the order of the time
of flight of the diode gap. The presence of a space
charge leads to a change in the distribution of the poten-
tial in the diode gap and a decrease in the electric field
at the cathode down to zero. This field depends on the
space charge distribution. But a decrease in the emission
current and an increase in diode voltage reduces the
effect of space charge and preserves the electric field at
the cathode. When the stationary diode voltage is
reached, if the diode current is substantially lower than
the cathode emission current (at high cathode tempera-
tures), the electric field at the cathode would be zero.
In a one-dimensional flat diode, the value of the di-
ode voltage determines the current density through the
diode and the potential distribution in the diode. The
steady stationary state of the flow is stable, in the sense
that the current density remains unchanged. With small
variations in the density of the space charge and veloci-
ty as functions of the spatial coordinate in the linear
approximation, the variation of the current density is
zero. The equilibrium distribution of space charge and
velocity is established.
1
3
2 212
3 32
2
0 0
0 0 0 0 0
1 10 0
0 0
0 0
0 0
0 0
0 0 0 0
4 ;
3
4 ; ;
9
( )( );
(v );
8 8; ;
27 27
0;
( ) 0.
d x
dx
d x x
dx
j v v
j j j v v
d dvv x x
dx dx
d dvv
dx dx
d dvj v v v x
dx dx
j
jρ ν j
ρ dρ d
d ρ dρ ρ d
ρ ρ
ρ ρ
ρd dρ ρ d ρ d
−
− −
≈
≈ − = − ≈ =
= + +
= + = + +
≈ ≈ −
+ ≡
= + = + =
ISSN 1562-6016. ВАНТ. 2018. №4(116) 29
REFERENCES
1. N.A. Khizhnyak, A.G. Limar. Status of the Khar-
kov’s Linear Collective Accelerator // Proceedings
of the Second International Conference on ADTT
and Applications, Kalmar, Sweden, June 3-7, 1996. v.
2, p. 1087-1089.
2. A.G. Lymar, P.A. Martynenko, N.A. Khizhnyak.
Development of a Collective Method of Ion Accel-
eration by Spatial Harmonics of Space Charge
Waves // Book of abstracts, XVI IWLPA, Alushta,
Crimea, September 6-12, 1999 / Kharkov: NSC KIPT,
1999, p. 117.
3. A.G. Lymar, P.A. Martynenko, N.A. Khizhnyak.
Slozhnoe povedenie v modeli elektronnoy pushki s
termokatodom // Problems of Atomic Science and
Technology. Series “Plasma Electronics and New
Methods of Acceleration”. 1998, № 1(1), p. 79 (in
Russian).
4. A.G. Lymar, P.A. Martynenko, V.A. Popov. Ion
Source of Reactive Gases with Decreased Neutral
Gas Inleakage // Problems of Atomic Science and
Technology. Series “Plasma Physics”. 2005. № 2,
p. 173-175.
5. P.A. Martynenko. The Forming System Simulation
for Reactive Gas Ion Source with Decreased Neutral
Gas Inleakage // Problems of Atomic Science and
Technology. Series “Plasma Physics”. 2017, № 1,
p. 152-154.
Article received 08.06.2018
ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ МНОГОИНЖЕКТОРНЫХ СИСТЕМ
С ТОКОМ ЭМИССИИ, ОПРЕДЕЛЯЕМЫМ ЗАКОНОМ ЛЕНГМЮРА
П.А. Мартыненко
Работа посвящена исследованию возможности расчета электронного и ионного инжекторов для системы,
использованной в модели коллективного ускорителя. Приведены результаты численных расчетов траекто-
рий заряженных частиц в трехэлектродной структуре. Обсуждается сложное поведение при численных рас-
четах пучков с током, ограниченным пространственным зарядом, методом трубок тока. Приводится способ
выбора параметра релаксации тока эмиссии инжектора, при котором после завершения переходного процес-
са в расчете достигается стационарное состояние пучка. Проведено сравнение результатов расчета с экспе-
риментальными данными как для сильноточного инжектора электронов, так и для термоэмиттера ионов ще-
лочных металлов.
ЧИСЕЛЬНЕ МОДЕЛЮВАННЯ БАГАТОІНЖЕКТОРНИХ СИСТЕМ
З ЕМІСІЙНИМ СТРУМОМ, ЗГІДНО ЗАКОНУ ЛЕНГМЮРА
П.О. Мартиненко
Робота присвячена дослідженню можливості розрахунку електронного та іонного інжекторів для системи,
використаної в моделі колективного прискорювача. Наведено результати чисельних розрахунків траєкторій
заряджених частинок у триелектродній структурі. Обговорюється складна поведінка при чисельних розра-
хунках пучків зі струмом, обмеженим просторовим зарядом, методом трубок струму. Наводиться спосіб
вибору параметра релаксації емісійного струму інжектора, при якому після завершення перехідного процесу
в розрахунку досягається стаціонарний стан пучка. Проведено порівняння результатів розрахунку з експе-
риментальними даними як для сильнострумового інжектора електронів, так і для термоеміттера іонів луж-
них металів.
|