Wide range electron energy adjustment at two-section RF linac
The results of numerical electron energy adjustment simulation at the exit of two-section RF linac in a wide range are presented. It is shown that energy of particles can be varied at the range of 15...94 MeV . Other beam parameters vary within tolerance limits at beam energy adjustment due to kee...
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 2009 |
| Автори: | , , , , |
| Формат: | Стаття |
| Мова: | Англійська |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2009
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Wide range electron energy adjustment at two-section RF linac / K.Yu. Kramarenko, V.A. Kushnir, V.V. Mytrochenko, A.M. Opanasenko, S.O. Perezhogin // Вопросы атомной науки и техники. — 2009. — № 5. — С. 130-133. — Бібліогр.: 9 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859907909272469504 |
|---|---|
| author | Kramarenko, K.Yu. Kushnir, V.A. Mytrochenko, V.V. Opanasenko, A.M. Perezhogin, S.O. |
| author_facet | Kramarenko, K.Yu. Kushnir, V.A. Mytrochenko, V.V. Opanasenko, A.M. Perezhogin, S.O. |
| citation_txt | Wide range electron energy adjustment at two-section RF linac / K.Yu. Kramarenko, V.A. Kushnir, V.V. Mytrochenko, A.M. Opanasenko, S.O. Perezhogin // Вопросы атомной науки и техники. — 2009. — № 5. — С. 130-133. — Бібліогр.: 9 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | The results of numerical electron energy adjustment simulation at the exit of two-section RF linac in a wide range
are presented. It is shown that energy of particles can be varied at the range of 15...94 MeV . Other beam parameters
vary within tolerance limits at beam energy adjustment due to keeping the bunches at the travelling wave crest of
self-consistent field in the linac sections.
Представленi результати чисельного моделювання процесу регулювання енергiї електронiв на виходi
двохсекцiйного резонансного прискорювача в широких межах. Показано, що енергiя частинок може
змiнюватися в межах 15...94 МэВ, тодi як решта параметрiв пучка змiнюється в допустимих межах
завдяки пiдтримцi згусткiв на гребенi хвилi самоузгодженого поля.
Представлены результаты численного моделирования процесса регулирования энергии электронов на
выходе двухсекционного резонансного ускорителя в широких пределах. Показано, что энергия частиц
может изменяться в пределах 15...94 МэВ, тогда как остальные параметры пучка изменяются в допустимых пределах благодаря поддержанию сгустков на гребне волны самосогласованного поля.
|
| first_indexed | 2025-12-07T16:01:04Z |
| format | Article |
| fulltext |
THEORY AND TECHNICS OF PARTICLE ACCELERATION
WIDE RANGE ELECTRON ENERGY ADJUSTMENT AT
TWO-SECTION RF LINAC
K.Yu. Kramarenko, V.A. Kushnir, V.V. Mytrochenko∗,
A.M. Opanasenko, S.O. Perezhogin
National Science Center ”Kharkov Institute of Physics and Technology”, 61108, Kharkov, Ukraine
(Received June 16, 2009)
The results of numerical electron energy adjustment simulation at the exit of two-section RF linac in a wide range
are presented. It is shown that energy of particles can be varied at the range of 15...94 MeV . Other beam parameters
vary within tolerance limits at beam energy adjustment due to keeping the bunches at the travelling wave crest of
self-consistent field in the linac sections.
PACS: 41.75.Ht, 25.20.-x
1. INTRODUCTION
At present there’s the lack of information on cross-
sections of many-particle photonuclear reactions for
most nuclei. The reactions on nuclei that are placed
far from β stability band and have changed relation
between coulomb and nuclear interaction are of par-
ticular interest. The serious problem at the mod-
ern stage of nuclear power engineering is to develop
the subcritical nuclear reactors controlled by electron
linacs. Obtaining experimental data on cross-sections
as well as on neutron yield in multi-neutron photonu-
clear reactions on various isotopes are critical issue at
solving the problem especially at γ-quantum energy
in the range of 40...100 MeV where experimental data
is almost absent while theoretical models are unreli-
able [1]. To carry out the experiments aimed to ob-
tain experimental quantitative data it is necessary to
have specific apparatuses, particularly electron linac
with beam energy that can be smoothly adjusted in
a wide range, preferably from 20 through 100 MeV .
For this matter, an electron linac with maximum en-
ergy of 100 MeV and average current of 6 µA [2] has
been created at NSC KIPT on the basis of the ex-
isted linac LU − 40 with maximal beam energy of
40 MeV . The key elements of the linac are diode elec-
tron gun, injection system and two travelling wave
accelerating sections. Increase of maximal beam en-
ergy has been obtained by replacing the old acceler-
ating section with new ones that have higher shunt
impedance (so called ”Kharkov-85” section type [3]).
At the reconstruction of LU − 40 linac, besides max-
imal beam energy increase, it was necessary to solve
the problem of wide range beam energy adjustment
that is very important for nuclear-physical researches.
Beam energy at the exit of the first section of the
two-section linac is usually well relativistic. For ex-
ample, at the reconstructed linac that energy in the
nominal mode must be about 50 MeV . In such case,
at the very short electron bunches, energy of parti-
cles can be changed by a few methods. In particular,
the acceleration of electron bunches off-crest of trav-
elling wave in the second section allows to change
particle energies in a wide range [2]. Obviously, off-
crest acceleration leads to energy spectrum widening
at finite bunch length. Acceleration or deceleration
of particles at the travelling wave crest with vari-
able amplitude can be alternative method of beam
energy adjustment. In our opinion this method is
more acceptable concerning finite bunch length. In
order to study this method efficiency, the simulation
of self-consistent beam dynamics in the reconstructed
linac has been carried out. Because of high shunt
impedance of the ”Kharkov-85” sections simulation
of self-consistent beam dynamics is reasonable and
can get more adequate results comparing with ”given
field” approach simulation. Preliminary analysis has
shown that even at beam current about 100 mA beam
loading effect causes significant influence on beam pa-
rameters.
2. SIMULATION OF BEAM DYNAMIC
The simulation has been carried out with the com-
puter code developed by the authors [4], [5], [6]
that is based on use of the SUPERFISH [7] and
PARMELA [8] codes. The developed code sim-
ulates self-consistent dynamics of intense electron
beam in linacs consisted of standing wave and travel-
ing wave sections taking into account space charge
effect and transients. Beam dynamics in electron
source (thermionic diode gun) was simulated with the
EGUN code [9].
The following parameters have been used at sim-
ulation: pulse current at the injector exit 66 mA;
current pulse duration 1.6 µs; pulse duration of RF
power supply 3 µs. Values of RF power supply at kly-
∗Corresponding author E-mail address: mitvic@kipt.kharkov.ua
130 PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY, 2009, N5.
Series: Nuclear Physics Investigations (52), p.130-133.
stron outputs can be varied in a range from 0 through
16 MW by adjusting amplitude of high voltage pulses
at outputs of klystron modulators. The reconstructed
linac has been configured so that the injector system
and the first accelerating section are supplied with
RF power from the same klystron. Part of klystron
output power canalized to the injector through di-
rectional coupler with minimal attenuation of 11 dB.
The simulation has shown that optimal RF power
supply of the injector is 0.75 MW . Therefore mini-
mal RF power that can be used to supply the first
accelerating section is 9.4 MW . Maximal beam en-
ergy at the linac exit can be obtained when RF
power supply of each section are 16 MW (see second
column of Table 1 and Fig.1). In this case beam
energy is 94 MeV . It is necessary to note that energy
spread width substantially depends on beam loading
influence. The field amplitude excited in the sections
by accelerated particles is substantial to the total ac-
celerating field. Steady state acceleration is set after
accelerating sections are filled with fields associated
both with RF generator and particles (filling time is
0.92 µs in our case). To diminish influence of beam
loading on beam energy, so called ∆T scheme was
used. It means that current pulses have been injected
into acceleration section at the moment of time when
the section is not yet filled with RF power from the
klystron. Despite simulation has shown that optimal
time delay between RF and current pulses is 0.8 µs or
0.87 µs fraction of the section filling time, full beam
loading compensation has not been obtained. For
further diminishing influence of beam loading onto
beam energy it is necessary to decrease the beam
0 20 40 60 80 100
0
2
4
6
8
10
12
14
x 10
4
W (MeV)
A
rb
. U
ni
ts
Fig.1. Beam energy spectrum at maximal energy
current. At constant RF power supply of the first
section (16 MW ) beam energy at the linac exit can
be smoothly changed by gradual decreasing of RF
power supply of the second section with simultane-
ous adjustment of it phase to provide about on-crest
acceleration. At zero RF power supply of the second
section its wave phase velocity needs to be changed
from the velocity of light, for example by changing
section temperature far away from operation temper-
ature, to diminish excitation of RF fields by particles
traveled through the section. In this case it is possi-
ble to expect that energy parameters of beam at the
linac exit are the same as that at the exit of the first
section. As simulation has shown (see third column
in Table 1) the minimal beam energy that can be
obtained with this approach is 48 MeV .
Table 1. Beam parameters at the linac exit
RF power supply (MW ) 16+16 16 9.4* 9.4**
Beam current (mA) 63 63 61.5 61.3
Mean energy (MeV ) 89.3 45 34.6 32.2
Peak energy (MeV ) 94.3 48 36.1 32.6
Energy spread width for 70% of particules (%) 5.4 8.2 5.9 8.9
Energy spread width at the half of spectrum maximum (FWHM) (%) 0.5 2.4 0.5 0.5
Bunch phase length for 70 % of particules (deg.) 17.1 17.6 17,1 17.1
Rms beam radius (mm) 0.71 0.73 0.76 1.2
Normalized emittance (mm ·mrad) 6 6 5 5
* second section is detuned (wave phase velocity is not equal to the light velocity)
** second section is tuned
Further beam energy decreasing can be obtained
by decreasing RF power supply of the first section.
Simulating results of beam dynamics at minimal RF
power of 9.4 MW are presented in the forth column
of Table 1. Simulation also has been performed for
the similar case but when phase velocity of accelerat-
ing wave in the second section was equal to velocity
of the light. The results are presented in the fifth
column of Table 1. Beam energy is lower in this
case because of particles interaction with the section
(influence of beam loading). Thus, the simulation
has shown that beam energy can be changed in a
range from 33 through 94MeV by level adjusting of
RF power supply keeping bunches at the travelling
wave crest in the second section and manipulating
with wave phase velocity in that section. It is im-
portant to note that changes of beam performances
excluding beam energy are not significant. To pro-
vide lower beam energy compared with 33 MeV it is
necessary to inject bunches into the second section
131
at decelerated phase of travelling wave generated by
RF power supply. Simulation has been performed
for two levels of RF power supply of the second
section 2 MW and 1 MW at several values of time
delay between RF and current pulses. The simu-
lation has shown that beam loading in the second
”decelerated” section is the essential cause of beam
energy spread. Optimal delays between RF and cur-
rent pulses for cases of maximal beam acceleration
in both sections and substantial beam deceleration
in the second section are quite different. It can be
seen from Table 2 that change of the time delay
from 0.8 µs to 0.6 µs causes marked improvement of
energy spread width from 24 % to 12% while other
beam parameters, for example, beam size and bunch
phase length vary within tolerance limits. Possible
explanation of this feature is following. Beam load-
ing is the particle deceleration in self-excited field,
so if we decelerate the particles in the field excited
by the external RF generator both fields act in the
same direction and influence of transient is higher.
To partially compensate this influence it is necessary
to have lower energy of particles at the exit of the
first section at the beginning of a current pulse com-
pared with the case of maximal acceleration, because
shorter time delay causes lower energy of particles at
the beginning of current pulse. Fig.2 and Fig.3 show
energy spreads at the linac exit at the time delay
of 0.6 µs. Curve features at energies that are higher
than energy of peaks (additional peak in Fig.2 and
step in Fig.3) are caused by the influence of transient.
0 5 10 15 20 25
0
2
4
6
8
x 10
4
W (MeV)
A
rb
. U
ni
ts
Fig.2. Beam energy spread at deceleration in the
second section with RF power supply of 2 MW
0 5 10 15 20 25
0
2
4
6
8
10
x 10
4
W (MeV)
A
rb
. U
ni
ts
Fig.3. Beam energy spread at deceleration in the
second section with RF power supply of 1 MW
Table 2. Beam parameters at the linac exit
RF power supply of the second section (MW ) 2 2 1
Time delay (µs) 0.8 0.6 0.6
Beam current (mA) 61.2 61.6 61.7
Mean energy (MeV ) 15.4 14.5 19.2
Peak energy (MeV ) 14.5 14.5 19.7
Energy spread width for 70% of particules (%) 24.2 12.2 8.5
FWHM energy spread (%) 0.5 1.0 0.5
Bunch phase length for 70 % of particules (deg.) 17.7 19.5 19.4
Rms beam radius (mm) 1.76 2.06 1.84
Normalized emittance (mm ·mrad) 6 6 6
3. THE CONCLUSION
The simulation carried out has shown that the re-
constructed linac can provide electrons energy in a
range of 15...94 MeV . Other beam parameters vary
within tolerance limits at beam energy adjustment
due to keeping bunches on-crest of self-consistent field
of travelling wave in the linac sections. The results
obtained are of great value to carry out the experi-
ments on wide electron beam energy adjustment at
the exit of LU − 40 which is is the base for obtaining
experimental data on cross-sections as well as on neu-
tron yield in multi-neutron photonuclear reactions on
various isotopes.
4. NOTES
This research work is supported by NAS of Ukraine
(Grant range beam energy adjustment at the LU−40
linac No. X − 9− 242).
132
References
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2. K.I. Antipov, M.I. Ayzatsky, Yu.I. Akchurin, et
al. S-Band Electron Linac with Beam Energy
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3. E.Z. Biller, A.N. Dovbhya, V.A. Kushnir, et al.
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4. V.A. Kushnir, V.V. Mytrochenko,
A.N. Opanasenko. Simulations of Transient
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ropean Particle Accelerator Conference. Paris,
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5. V.V. Mytrochenko, A.N. Opanasenko. Simu-
lation Technique for Study of Transient Self-
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6. V.V. Mytrochenko, A.N. Opanasenko. Study of
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7. J.H. Billen, L.M. Young. POISSON/ SUPER-
FISH on PC compatibles // Particle Accelerator
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РЕГУЛИРОВАНИЕ ЭНЕРГИИ ЭЛЕКТРОНОВ НА ВЫХОДЕ ДВУХСЕКЦИОННОГО
РЕЗОНАНСНОГО УСКОРИТЕЛЯ
К.Ю. Крамаренко, В.А. Кушнир, В.В. Митроченко, А.Н. Опанасенко, С.А. Пережогин
Представлены результаты численного моделирования процесса регулирования энергии электронов на
выходе двухсекционного резонансного ускорителя в широких пределах. Показано, что энергия частиц
может изменяться в пределах 15...94МэВ, тогда как остальные параметры пучка изменяются в допу-
стимых пределах благодаря поддержанию сгустков на гребне волны самосогласованного поля.
РЕГУЛЮВАННЯ ЕНЕРГIЇ ЕЛЕКТРОНIВ НА ВИХОДI ДВОХСЕКЦIЙНОГО
РЕЗОНАНСНОГО ПРИСКОРЮВАЧА
К.Ю. Крамаренко, В.А. Кушнiр, В.В. Митроченко, А.М. Опанасенко, С.О. Пережогiн
Представленi результати чисельного моделювання процесу регулювання енергiї електронiв на виходi
двохсекцiйного резонансного прискорювача в широких межах. Показано, що енергiя частинок може
змiнюватися в межах 15...94МэВ, тодi як решта параметрiв пучка змiнюється в допустимих межах
завдяки пiдтримцi згусткiв на гребенi хвилi самоузгодженого поля.
133
|
| id | nasplib_isofts_kiev_ua-123456789-96649 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T16:01:04Z |
| publishDate | 2009 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Kramarenko, K.Yu. Kushnir, V.A. Mytrochenko, V.V. Opanasenko, A.M. Perezhogin, S.O. 2016-03-18T19:52:21Z 2016-03-18T19:52:21Z 2009 Wide range electron energy adjustment at two-section RF linac / K.Yu. Kramarenko, V.A. Kushnir, V.V. Mytrochenko, A.M. Opanasenko, S.O. Perezhogin // Вопросы атомной науки и техники. — 2009. — № 5. — С. 130-133. — Бібліогр.: 9 назв. — англ. 1562-6016 PACS: 41.75.Ht, 25.20.-x https://nasplib.isofts.kiev.ua/handle/123456789/96649 The results of numerical electron energy adjustment simulation at the exit of two-section RF linac in a wide range are presented. It is shown that energy of particles can be varied at the range of 15...94 MeV . Other beam parameters vary within tolerance limits at beam energy adjustment due to keeping the bunches at the travelling wave crest of self-consistent field in the linac sections. Представленi результати чисельного моделювання процесу регулювання енергiї електронiв на виходi двохсекцiйного резонансного прискорювача в широких межах. Показано, що енергiя частинок може змiнюватися в межах 15...94 МэВ, тодi як решта параметрiв пучка змiнюється в допустимих межах завдяки пiдтримцi згусткiв на гребенi хвилi самоузгодженого поля. Представлены результаты численного моделирования процесса регулирования энергии электронов на выходе двухсекционного резонансного ускорителя в широких пределах. Показано, что энергия частиц может изменяться в пределах 15...94 МэВ, тогда как остальные параметры пучка изменяются в допустимых пределах благодаря поддержанию сгустков на гребне волны самосогласованного поля. This research work is supported by NAS of Ukraine (Grant range beam energy adjustment at the LU −40 linac No. X − 9 − 242). en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Теория и техника ускорения частиц Wide range electron energy adjustment at two-section RF linac Регулювання енергiї електронiв на виходi двохсекцiйного резонансного прискорювача Регулирование энергии электронов на выходе двухсекционного резонансного ускорителя Article published earlier |
| spellingShingle | Wide range electron energy adjustment at two-section RF linac Kramarenko, K.Yu. Kushnir, V.A. Mytrochenko, V.V. Opanasenko, A.M. Perezhogin, S.O. Теория и техника ускорения частиц |
| title | Wide range electron energy adjustment at two-section RF linac |
| title_alt | Регулювання енергiї електронiв на виходi двохсекцiйного резонансного прискорювача Регулирование энергии электронов на выходе двухсекционного резонансного ускорителя |
| title_full | Wide range electron energy adjustment at two-section RF linac |
| title_fullStr | Wide range electron energy adjustment at two-section RF linac |
| title_full_unstemmed | Wide range electron energy adjustment at two-section RF linac |
| title_short | Wide range electron energy adjustment at two-section RF linac |
| title_sort | wide range electron energy adjustment at two-section rf linac |
| topic | Теория и техника ускорения частиц |
| topic_facet | Теория и техника ускорения частиц |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/96649 |
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