The electron injector for linac of the "NESTOR" storage ring
Results of the bunching system design and electron motion simulation in the compact S – band injector are presented.
 The injector consists of the low-voltage diode electron gun and bunching system based on the resonant system
 with the evanescent oscillations. The amplitude of RF el...
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| Published in: | Вопросы атомной науки и техники |
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| Date: | 2006 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2006
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| Cite this: | The electron injector for linac of the "NESTOR" storage ring / M.I. Aizatsky, V.A. Kushnir, V.V. Mytrochenko, S.A. Perezhogin, V.Ph. Zhiglo // Вопросы атомной науки и техники. — 2006. — № 2. — С. 94-96. — Бібліогр.: 10 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860233292386664448 |
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| author | Aizatsky, M.I. Kushnir, V.A. Mytrochenko, V.V. Perezhogin, S.A. Zhiglo, V.Ph. |
| author_facet | Aizatsky, M.I. Kushnir, V.A. Mytrochenko, V.V. Perezhogin, S.A. Zhiglo, V.Ph. |
| citation_txt | The electron injector for linac of the "NESTOR" storage ring / M.I. Aizatsky, V.A. Kushnir, V.V. Mytrochenko, S.A. Perezhogin, V.Ph. Zhiglo // Вопросы атомной науки и техники. — 2006. — № 2. — С. 94-96. — Бібліогр.: 10 назв. — англ. |
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| container_title | Вопросы атомной науки и техники |
| description | Results of the bunching system design and electron motion simulation in the compact S – band injector are presented.
The injector consists of the low-voltage diode electron gun and bunching system based on the resonant system
with the evanescent oscillations. The amplitude of RF electrical field grows along the axis of the bunching system.
The resonance system optimization has been carried out that allows obtaining of the electron bunch with the
phase length less than 10° and energy spread less than 5% (for 70% particles) at the injector exit.
В работе приведены результаты расчета группирующей системы и моделирование движения электронов в инжекторе S–диапазона. Инжектор состоит из низковольтной диодной электронной пушки и группирователя на основе резонансной системы с нераспространяющимися колебаниями. В устройстве реализовано такое распределение поля на оси, при котором его амплитуда нарастает от точки инжекции электронов до выхода группирователя. Проведена оптимизация резонансной системы, которая позволяет получить на выходе инжектора электронные сгустки с фазовой протяженностью меньше 10 градусов и шириной энергетического спектра меньше 5% (для 70% частиц).
У роботі приведено результати розрахунку групуючої системи і моделювання руху електронів в
інжекторі S–діапазону. Інжектор складається з низьковольтної діодної електронної гармати та груповача на
основі резонансної системи з коливаннями, що не розповсюджуються. У пристрої реалізовано такий
розподіл поля на осі, при якому його амплітуда наростає від точки інжекції електронів до виходу груповача.
Проведена оптимізація резонансної системи, яка дозволяє одержати на виході інжектора електронні згустки
з фазовою протяжністю менше 10 градусів і шириною енергетичного спектру менше 5% (для 70% частинок).
|
| first_indexed | 2025-12-07T18:22:48Z |
| format | Article |
| fulltext |
THE ELECTRON INJECTOR FOR LINAC OF THE "NESTOR" STOR-
AGE RING
M.I. Aizatsky, V.A. Kushnir, V.V. Mytrochenko, S.A. Perezhogin, V.Ph. Zhiglo
NSC KIPT, Kharkov, Ukraine
E-mail: psa@kipt.kharkov.ua
Results of the bunching system design and electron motion simulation in the compact S – band injector are pre-
sented. The injector consists of the low-voltage diode electron gun and bunching system based on the resonant sys-
tem with the evanescent oscillations. The amplitude of RF electrical field grows along the axis of the bunching sys-
tem. The resonance system optimization has been carried out that allows obtaining of the electron bunch with the
phase length less than 10° and energy spread less than 5% (for 70% particles) at the injector exit.
PACS: 12.20.-m, 13.40.-f, 13.60-Hb, 13.88.+e
1. INTRODUCTION
An increase of the electric field along the axis of a
resonant system of an injector allows improving of short
bunches formation at comparatively small energy spread
[1-3]. There is suggested an injector [4] in which to cre-
ate an increasing field along the axis of the resonant sys-
tem, a section of periodic disc-loaded waveguide excit-
ed in the stop-band was applied. The choice of such a
resonant system is based on system easiness in tuning
for obtaining the increasing field distribution. The more
detailed particles dynamic analysis has shown that the
choice of identical cavity lengths in the middle part of
the resonant system is not optimal for the bunching pro-
cess.
When creating the linac for the storage ring
“NESTOR” [5] the purpose was to obtain the minimum
energy spectrum width (∆W/W<1%) at the linac exit.
To decrease the energy spread at the injector exit it is
necessary to decrease the bunch phase length at the
linac input. It is possible to achieve such beam parame-
ters at the phase length of the electron beam at the injec-
tor exit ∆ϕ<10°.
The purpose of this research is to develop the elec-
tron injector providing the minimum phase bunch size at
the injector exit at the energy spread (∆W/W<5%) and
normalized emittance (εn rms<15 mm·mrad). In the base
of the injector being developed there is the injector de-
veloped and produced for the linac at the energy up to
100 MeV [6].
2. BUNCHING SYSTEM
To calculate the electrodynamics characteristics of
the resonant system the SUPERFISH group of codes has
been used [7]. The simulation of particle dynamics in
the diode gun and in the bunching resonant system has
been carried out with the use of the EGUN code [8] and
the PARMELA code [9]. To achieve the phase bunch
length at the bunching system exit ∆ϕ<10° there was
applied a procedure of resonant system optimization
represented in Ref. [10]. The main point of the opti-
mization was to select the field distribution on the sys-
tem axis that provides minimum bunches phase length.
The required field distribution is achieved by the varia-
tion of the field amplitudes in each of the resonators and
their appropriate lengths change.
Based upon the optimization procedure represented,
the injector resonant system has been calculated and de-
veloped. In Fig.1 the optimized resonant system of the
injector is shown.
Fig. 1. Resonant system geometry and space field
distribution
Besides the resonator sizes changing, the injector
construction has been modified as well. In the initial in-
jector construction the RF power is supplied by the rect-
angular waveguide through the coupling window that
resulted in the radial inhomogeneous field. To eliminate
that disadvantage there was suggested to supply the RF
power into the resonant system through the coaxial
waveguide.
As stated before [6], while operating the injector
there was observed an instability. We explained that as
the poliphase secondary emission discharge in the first
resonator. To eliminate that phenomenon the geometry
of the first resonator has been changed (see Fig.1).
By the simulation results the main electrodynamics
characteristics of the bunching system have been de-
fined (the results are presented in Table 1).
Table 1. Electrodynamics characteristics of the
bunching system
Parameter Value
Operating frequency fO, MHz 2797.15
Quality factor 12354
Shunt impedance, MOhm/m 18.4
Power losses in walls, kW 558
Maximum field on the axis, MV/m 39.4
The coupling coefficient of the feeder
with the resonance system 3.8
The coupling coefficient of the feeder with the reso-
nance system has been chosen according to the duration
of the transient processes in the resonant system. The re-
sulting optimized field distribution on the resonant sys-
tem axis is presented in Fig.2.
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PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2006. № 2.
Series: Nuclear Physics Investigations (46), p.94-96.94
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
z, cm
E
/E
ma
x
Fig.2. Distribution of on-axis field after the
optimization
To ascertain the influence of the operating frequency
change (f=fO±0.2 MHz) onto the field distribution in the
resonant system and onto the beam characteristics at the
injector exit, the appropriate calculations have been per-
formed for ∆f=fO±f. In Table 2 there are shown the val-
ues of the electric field strength relative variation to-
wards the field in the fifth resonator on the resonant sys-
tem axis for each resonator according to the operating
frequency change.
Table 2. The electric field relative variation on the sys-
tem axis in each resonator at the operating frequency
change
Resonator’s number 1 2 3 4 5
∆E/E (-0.2 MHz), % -1.9 -1.6 -0.9 -0.6 0
∆E/E (+0.2 MHz), % 1.9 1.5 0.9 0.6 0
As it is seen from the table, the frequency change
within rather large limits does not result into the sub-
stantial field redistribution in the resonant system.
3. RESULTS OF BEAM DYNAMICS SIMU-
LATION IN THE INJECTOR
The simulation has been carried out for an electron
beam with the initial energy 25 keV and current
245 mA, with taking into account the space charge
force. To take space charge forces correctly, the input
beam was represented by a bunch with length of 5βλ,
where β is initial relative speed of particles, λ is the op-
erating wavelength.
To reduce the influence of space charge on a
transversal emittance, the electron gun should be placed
as close as possible to the bunching system. Therefore,
in the developed buncher the inlet opening for beam in-
jection is an anode of the gun. The computational pa-
rameters of the gun and beam characteristic without tak-
ing into account the influence of a RF field are listed in
Table 3. The calculations have been carried out with the
code EGUN [8].
As a result of electron beam dynamics simulations,
the beam characteristics at the injector exit have been
defined (see Table 4 and Fig.3). In Table 4 there also
are presented the electron bean characteristics at the in-
jector exit at the change of the operating frequency
within ±0.2 MHz. The beam characteristics at the injec-
tor exit are shown for the case when the filed amplitudes
in the fifth resonator are the same.
Table 3. Computational parameters of the gun and
beam characteristics
Parameter Value
Cathode voltage, kV -25
Cathode radius, mm 2.5
Normalize beam emittance (1σ), π⋅mm⋅mrad 4.1
Distance from the front cut of the anode
aperture to the beam waist, mm 19
The beam radius in the waist, mm 1.1
Beam current, mA 245
Table 4. Beam characteristics at the injector exit
Name Values
fO fO-0.2MHz fO+0.2MHz
Normalized emittance (1σ)
, εrms x,y π⋅mm⋅mrad 9 8.8 9
Beam size 4σx,y, mm 2.5 2.5 2.5
Bunch phase length ∆ϕ
(for 70% of particles),° 7.7 8.9 7.9
Energy spread ∆W/W, (for
70% of particles), % 3.9 3.9 3.9
Maximal energy Wmax, keV 1022 1022 1022
Average energy Wavr, keV 948 947 947
Energy in the maximum of
the energy spectrum, keV 1012 1012 1012
Widths of the vertical and
horizontal beam profiles
(for 70% of particles), mm
1 1.1 0.96
Capture coefficient kз, % 89.3 89.5 89.2
As it is seen from the table, with the change of the
operating frequency the beam characteristics change in-
significantly. For instance, the phase length relative
change does not exceed 15%.
2004
1502
1002
501
0
2276
1707
1138
569
0
50
25
0
-25
-50
796
597
398
199
0
0 500 1000 1500 2000 -0.5 -0.25 0 0.25 0.5
X, cm.Phase
X
`,
m
ra
d
A
rb
. u
ni
ts
X, cm.Energy, keV.
-180 -90 0 90 180 -0.5 -0.25 0 0.25 0.5
A
rb
. u
ni
ts
A
rb
. u
ni
ts
Fig.3. Beam characteristics at the injector exit
In the simulation there have been obtained the de-
pendences of the energy and phase spectrum width, the
average electron energy, the emittance, the capture coef-
ficient at the injector exit at various values of the accel-
erating field (see Fig.4). The values of the energy and
phase spectrum are given for 70% of all the particles at
the injector exit.
___________________________________________________________
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2006. № 2.
Series: Nuclear Physics Investigations (46), p.94-96.94
0
10
20
30
40
50
60
70
80
90
100
18 21 24 27 30 33 36 39 42 45 48
E (MV/m) максимальное поле в резонансной системе
∆W
/W
(%
),
∆ϕ
(°
),
ε r
m
s (
m
m
m
ra
d)
,
k c
ap
tu
re
(%
)
0
0.12
0.24
0.36
0.48
0.6
0.72
0.84
0.96
1.08
1.2
W
av
r (
M
eV
)
kcapture
∆ W/W
∆ ϕ
ε rms
Wavr
Fig. 4. The dependences of the energy and phase
spectrum width, the average electron energy, the
emittance, the capture coefficient at the injector exit
at various values of the accelerating field
As it is shown in the figure, at the change of the ac-
celerating field amplitude from –12% to 8% of the opti-
mal value the phase spectrum width remains within 10°.
4. CONCLUSIONS
Based upon our developed conception of using the
periodic structures with evanescent oscillations for the
bunching and preliminary accelerating of the electron
beam, the simulation has been carried out and the con-
struction of the new injector system linac with the reso-
nant system optimized geometry has been developed.
The injector with the optimized field distribution allows
electron bunches to be formed effectively and to be ac-
celerated from an initial energy of 25 keV up to 1 MeV
at a current up to 245 mA. The developed bunching sys-
tem will allow obtaining of an electron beam at the linac
exit for the “NESTOR” storage ring with the following
basic parameters: Wavr=948 keV, ∆W/W=3,9%, εrms x,y=9
π⋅mm mrad, ∆ϕ=7.7°.
REFERENCES
1. A.N. Lebedev, A.V. Shalnov. Base physics and
techniques accelerators. M.: “Energoatomizdat”,
1991.
2. N.M. Bogomolov Линейное ускорение заряжен-
ных частиц на обратной волне // DAN USSR.
1973, v.208, №6, p.113-113.
3. M.S. Avilov, A.V. Novochatsky. Single bunch
compression in exponent field. Proc. of the XIV
Workshop on charged particle accelerators, Protvi-
no. 1994, v.3, p.181-183 (in Russian).
4. M.I. Ayzatsky, E.Z. Biller, V.A. Kushnir et al.
Electron injector based on resonance system with
evanescent oscillations // Problems of Atomic Sci-
ence and Technology. Series: Nuclear Physics In-
vestigations. 2004, №1, p.60-62.
5. P. Gladkikh et al. Status of Kharkov X-ray genera-
tor based on Compton scattering NESTOR. Proc. of
EPAC`04. Lucerne. 2004.
6. M.I. Ayzatsky, E.Z. Biller, V.A. Kushnir et al. Test
results of injector based on resonance system with
evanescent oscillations. Proc. of EPAC`04.
Lucerne. 2004.
7. J.H. Billen, L.M. Young. POISSON/SUPERFISH
on PC compatibles. Proc. 1993 Particle Accelerator
Conf. Washington. 1993, p.790-792.
8. W.B. Herrmannsfeldt. EGUN: Electron Optics
Program. SLAC-PUB-6729, Stanford Linear Ac-
celerator Center, 1994.
9. L.M.Young. PARMELA. Preprint LA-UR-96-1835,
Los Alamos: 1996, c.93.
10. S.A. Perezhogin, N.I. Ayzatsky, K.Yu. Kra-
marenko. The optimization of the electron injector
resonant system based on the evanescent oscilla-
tions. Proc. of PAC`05. USA. 2005.
ИНЖЕКТОР ЭЛЕКТРОНОВ ДЛЯ ЛИНЕЙНОГО УСКОРИТЕЛЯ-НАКОПИТЕЛЯ “НЕСТОР”
Н.И. Айзацкий, В.А. Кушнир, В.В. Митроченко, С.А. Пережогин, В.Ф. Жигло
В работе приведены результаты расчета группирующей системы и моделирование движения электронов
в инжекторе S–диапазона. Инжектор состоит из низковольтной диодной электронной пушки и группирова-
теля на основе резонансной системы с нераспространяющимися колебаниями. В устройстве реализовано та-
кое распределение поля на оси, при котором его амплитуда нарастает от точки инжекции электронов до вы-
хода группирователя. Проведена оптимизация резонансной системы, которая позволяет получить на выходе
инжектора электронные сгустки с фазовой протяженностью меньше 10 градусов и шириной энергетического
спектра меньше 5% (для 70% частиц).
ІНЖЕКТОР ЕЛЕКТРОНІВ ДЛЯ ЛІНІЙНОГО ПРИСКОРЮВАЧА-НАКОПИЧУВАЧА “НЕСТОР”
М.І. Айзацький, В.А. Кушнір, В.В. Митроченко, С.О. Пережогін, В.Ф. Жигло
У роботі приведено результати розрахунку групуючої системи і моделювання руху електронів в
інжекторі S–діапазону. Інжектор складається з низьковольтної діодної електронної гармати та груповача на
основі резонансної системи з коливаннями, що не розповсюджуються. У пристрої реалізовано такий
розподіл поля на осі, при якому його амплітуда наростає від точки інжекції електронів до виходу груповача.
Проведена оптимізація резонансної системи, яка дозволяє одержати на виході інжектора електронні згустки
з фазовою протяжністю менше 10 градусів і шириною енергетичного спектру менше 5% (для 70% частинок).
86
1. INTRODUCTION
2. BUNCHING SYSTEM
3. RESULTS OF BEAM DYNAMICS SIMULATION IN THE INJECTOR
4. CONCLUSIONS
REFERENCES
ИНЖЕКТОР ЭЛЕКТРОНОВ ДЛЯ ЛИНЕЙНОГО УСКОРИТЕЛЯ-НАКОПИТЕЛЯ “НЕСТОР”
ІНЖЕКТОР ЕЛЕКТРОНІВ ДЛЯ ЛІНІЙНОГО ПРИСКОРЮВАЧА-НАКОПИЧУВАЧА “НЕСТОР”
|
| id | nasplib_isofts_kiev_ua-123456789-78779 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T18:22:48Z |
| publishDate | 2006 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Aizatsky, M.I. Kushnir, V.A. Mytrochenko, V.V. Perezhogin, S.A. Zhiglo, V.Ph. 2015-03-20T20:22:34Z 2015-03-20T20:22:34Z 2006 The electron injector for linac of the "NESTOR" storage ring / M.I. Aizatsky, V.A. Kushnir, V.V. Mytrochenko, S.A. Perezhogin, V.Ph. Zhiglo // Вопросы атомной науки и техники. — 2006. — № 2. — С. 94-96. — Бібліогр.: 10 назв. — англ. 1562-6016 PACS: 12.20.-m, 13.40.-f, 13.60-Hb, 13.88.+e https://nasplib.isofts.kiev.ua/handle/123456789/78779 Results of the bunching system design and electron motion simulation in the compact S – band injector are presented.
 The injector consists of the low-voltage diode electron gun and bunching system based on the resonant system
 with the evanescent oscillations. The amplitude of RF electrical field grows along the axis of the bunching system.
 The resonance system optimization has been carried out that allows obtaining of the electron bunch with the
 phase length less than 10° and energy spread less than 5% (for 70% particles) at the injector exit. В работе приведены результаты расчета группирующей системы и моделирование движения электронов в инжекторе S–диапазона. Инжектор состоит из низковольтной диодной электронной пушки и группирователя на основе резонансной системы с нераспространяющимися колебаниями. В устройстве реализовано такое распределение поля на оси, при котором его амплитуда нарастает от точки инжекции электронов до выхода группирователя. Проведена оптимизация резонансной системы, которая позволяет получить на выходе инжектора электронные сгустки с фазовой протяженностью меньше 10 градусов и шириной энергетического спектра меньше 5% (для 70% частиц). У роботі приведено результати розрахунку групуючої системи і моделювання руху електронів в
 інжекторі S–діапазону. Інжектор складається з низьковольтної діодної електронної гармати та груповача на
 основі резонансної системи з коливаннями, що не розповсюджуються. У пристрої реалізовано такий
 розподіл поля на осі, при якому його амплітуда наростає від точки інжекції електронів до виходу груповача.
 Проведена оптимізація резонансної системи, яка дозволяє одержати на виході інжектора електронні згустки
 з фазовою протяжністю менше 10 градусів і шириною енергетичного спектру менше 5% (для 70% частинок). en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Линейные ускорители заряженных частиц The electron injector for linac of the "NESTOR" storage ring Инжектор электронов для линейного ускорителя-накопителя “НЕСТОР” Інжектор електронів для лінійного прискорювача-накопичувача “НЕСТОР” Article published earlier |
| spellingShingle | The electron injector for linac of the "NESTOR" storage ring Aizatsky, M.I. Kushnir, V.A. Mytrochenko, V.V. Perezhogin, S.A. Zhiglo, V.Ph. Линейные ускорители заряженных частиц |
| title | The electron injector for linac of the "NESTOR" storage ring |
| title_alt | Инжектор электронов для линейного ускорителя-накопителя “НЕСТОР” Інжектор електронів для лінійного прискорювача-накопичувача “НЕСТОР” |
| title_full | The electron injector for linac of the "NESTOR" storage ring |
| title_fullStr | The electron injector for linac of the "NESTOR" storage ring |
| title_full_unstemmed | The electron injector for linac of the "NESTOR" storage ring |
| title_short | The electron injector for linac of the "NESTOR" storage ring |
| title_sort | electron injector for linac of the "nestor" storage ring |
| topic | Линейные ускорители заряженных частиц |
| topic_facet | Линейные ускорители заряженных частиц |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/78779 |
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