Photoinjector accelerating system for sub-mm high-power pulse source
Generation of high-intensity sub-mm electromagnetic radiation can be performed by means of the scheme that implies generation of radiation by short monochromatic bunch of electrons which is traveling through dielectric or corrugated capillary. Short bunch of electrons can be obtained by using of a p...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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| Цитувати: | Photoinjector accelerating system for sub-mm high-power pulse source / T.V. Bondarenko, S.M. Polozov // Вопросы атомной науки и техники. — 2012. — № 3. — С. 53-57. — Бібліогр.: 5 назв. — англ. |
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irk-123456789-1086652016-11-14T03:02:21Z Photoinjector accelerating system for sub-mm high-power pulse source Bondarenko, T.V. Polozov, S.M. Generation of high-intensity sub-mm electromagnetic radiation can be performed by means of the scheme that implies generation of radiation by short monochromatic bunch of electrons which is traveling through dielectric or corrugated capillary. Short bunch of electrons can be obtained by using of a photoinjector. R&D of accelerating systems of S-band photoinjector and analysis of electron bunch dynamics in this system are declared. The aim of the work is to find optimal model providing large value of efficiency and magnitude of accelerating field with low RF power. Different structure's types are considered to achieve this aim, such as 1.6 cell disk-loaded waveguide (DLW) and 3 cells and 2 half-cells of DLW. Structure based on 7 cells and 2 half-cells of DLW and travelling wave resonator (TWR) based system are analyzed to consider the possibility of increasing the electrical strength of the system and decreasing of requirements to RF power source. Results of electrodynamics characteristics analysis of accelerating structures resonant models and structures with power ports are presented. Electron bunch dynamics study results are also discussed. Для генерации мощного электромагнитного излучения терагерцового диапазона частот может быть использована схема, в которой излучение генерируется коротким монохроматическим сгустком электронов, пролетающим по диэлектрическому или гофрированному капилляру. Короткий сгусток электронов может быть сгенерирован с использованием фотоинжектора. В работе описывается разработка модели ускоряющей системы фотоинжектора десятисантиметрового диапазона частот для такого источника и проводится анализ динамики пучка электронов в такой структуре. Целью работы является разработка оптимальной модели, обеспечивающей максимальную эффективность и большую величину ускоряющего поля при минимальной мощности питания. Для этого были рассмотрены варианты ускоряющей системы, основанной на круглом диафрагмированном волноводе (КДВ) различных конфигураций: 1,6 ячейки КДВ, 3 целых ячейки и 2 полуячейки КДВ. Для рассмотрения возможности увеличения электрической прочности системы и снижения требований к источнику ВЧ-питания, рассмотрены модели с 7 целыми ячейками и 2 полуячейками КДВ и модель резонатора бегущей волны с 7 целыми ячейками и 2 полуячейками. Представлены результаты анализа электродинамических характеристик резонансных моделей ускоряющих структур и структур с вводами мощности. Приведены результаты исследования динамики пучка электронов в структурах. Для генерації потужного електромагнітного випромінювання терагерцового діапазону частот може бути використана схема, в якій випромінювання генерується коротким монохроматичним згустком електронів, які пролітають по діелектричному або гофрованому капіляру. Короткий згусток електронів може бути згенерований з використанням фотоінжектора. У роботі описується розробка моделі прискорюючої системи фотоінжектора десятисантиметрового діапазону частот для такого джерела і проводиться аналіз динаміки пучка електронів у такій структурі. Метою роботи є розробка оптимальної моделі, що забезпечує максимальну ефективність і велику величину прискорюючого поля при мінімальній потужності живлення. Для цього були розглянуті варіанти прискорюючої системи, заснованої на круглому діафрагмованому хвилеводі (КДХ) різних конфігурацій: 1,6 комірки КДХ, 3 цілих комірки та 2 напівкомірки КДХ. Для розгляду можливості збільшення електричної міцності системи і зниження вимог до джерела ВЧ-живлення, розглянуті моделі з 7 цілими комірками і 2 напівкомірками КДХ і модель резонатора біглої хвилі з 7 цілими комірками і 2 напівкомірками. Представлені результати аналізу електродинамічних характеристик резонансних моделей прискорюючих структур і структур з введеннями потужності. Наведено результати дослідження динаміки пучка електронів в структурах. 2012 Article Photoinjector accelerating system for sub-mm high-power pulse source / T.V. Bondarenko, S.M. Polozov // Вопросы атомной науки и техники. — 2012. — № 3. — С. 53-57. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS: 29.27.-A, 29.27.Bd http://dspace.nbuv.gov.ua/handle/123456789/108665 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Generation of high-intensity sub-mm electromagnetic radiation can be performed by means of the scheme that implies generation of radiation by short monochromatic bunch of electrons which is traveling through dielectric or corrugated capillary. Short bunch of electrons can be obtained by using of a photoinjector. R&D of accelerating systems of S-band photoinjector and analysis of electron bunch dynamics in this system are declared. The aim of the work is to find optimal model providing large value of efficiency and magnitude of accelerating field with low RF power. Different structure's types are considered to achieve this aim, such as 1.6 cell disk-loaded waveguide (DLW) and 3 cells and 2 half-cells of DLW. Structure based on 7 cells and 2 half-cells of DLW and travelling wave resonator (TWR) based system are analyzed to consider the possibility of increasing the electrical strength of the system and decreasing of requirements to RF power source. Results of electrodynamics characteristics analysis of accelerating structures resonant models and structures with power ports are presented. Electron bunch dynamics study results are also discussed. |
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Article |
| author |
Bondarenko, T.V. Polozov, S.M. |
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Bondarenko, T.V. Polozov, S.M. Photoinjector accelerating system for sub-mm high-power pulse source Вопросы атомной науки и техники |
| author_facet |
Bondarenko, T.V. Polozov, S.M. |
| author_sort |
Bondarenko, T.V. |
| title |
Photoinjector accelerating system for sub-mm high-power pulse source |
| title_short |
Photoinjector accelerating system for sub-mm high-power pulse source |
| title_full |
Photoinjector accelerating system for sub-mm high-power pulse source |
| title_fullStr |
Photoinjector accelerating system for sub-mm high-power pulse source |
| title_full_unstemmed |
Photoinjector accelerating system for sub-mm high-power pulse source |
| title_sort |
photoinjector accelerating system for sub-mm high-power pulse source |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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2012 |
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http://dspace.nbuv.gov.ua/handle/123456789/108665 |
| citation_txt |
Photoinjector accelerating system for sub-mm high-power pulse source / T.V. Bondarenko, S.M. Polozov // Вопросы атомной науки и техники. — 2012. — № 3. — С. 53-57. — Бібліогр.: 5 назв. — англ. |
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ISSN 1562-6016. ВАНТ. 2012. №3(79) 53
PHOTOINJECTOR ACCELERATING SYSTEM FOR
SUB-MM HIGH-POWER PULSE SOURCE
T.V. Bondarenko, S.M. Polozov
National Research Nuclear University MEPhI, Moscow, Russia
E-mail: smpolozov@mephi.ru
Generation of high-intensity sub-mm electromagnetic radiation can be performed by means of the scheme that
implies generation of radiation by short monochromatic bunch of electrons which is traveling through dielectric or
corrugated capillary. Short bunch of electrons can be obtained by using of a photoinjector. R&D of accelerating sys-
tems of S-band photoinjector and analysis of electron bunch dynamics in this system are declared. The aim of the
work is to find optimal model providing large value of efficiency and magnitude of accelerating field with low RF
power. Different structure's types are considered to achieve this aim, such as 1.6 cell disk-loaded waveguide (DLW)
and 3 cells and 2 half-cells of DLW. Structure based on 7 cells and 2 half-cells of DLW and travelling wave resona-
tor (TWR) based system are analyzed to consider the possibility of increasing the electrical strength of the system
and decreasing of requirements to RF power source. Results of electrodynamics characteristics analysis of accelerat-
ing structures resonant models and structures with power ports are presented. Electron bunch dynamics study results
are also discussed.
PACS: 29.27.-A, 29.27.Bd
1. INTRODUCTION
The gamma, electron or neutron facilities are used for
introscopy at present including cargo introscopy. They
are conventionally based on an electrostatic electron or
ion gun or accelerator. But such facility has one great
disadvantage because all of them are the radiation
sources and can to activate the cargo. New generation of
introscopy facilities with low activation are under de-
sign at present. The using of THz region radiation is one
of possible methods. The design of THz (or sub-mm)
radiation source is one of possible needs of photo guns.
One of such facility based on Cherenkov or Smith-
Parcell radiation given by short electron bunch with
MeV energy and special decelerating system was dis-
cussed in [1]. The radiation in ps and sub-ps bands can
be generated using this scheme. The electron bunch
must also have ps duration and 100…200 μm transverse
sizes. This condition follows as small width of irradiat-
ing capillary channel in which electromagnetic radiation
is induced.
Accelerating systems that are used in photo injectors
are conventionally based on disk-loaded waveguide
(DLW). Most widely used normal conducting photo
guns are based on 1.6 cells DLW and operate on stand-
ing wave mode. Electrodynamics characteristics com-
parison of 1.6 cell structure and traveling wave struc-
tures will done to investigate the possibility of develop-
ing more effective structures. Such structures must to
have high rate of beam exit power in respect to low RF
power and low possibility of electrical breakdown.
Beam dynamics in all modeled systems with beam pa-
rameters corresponding to photoelectron beam emitted
from cathode in typical photoinjector has also been in-
vestigated.
2. 1.6 CELLS ACCELERATING
STRUCTURE
1.6 cells accelerating structure was computed for
2856 MHz MW source operating frequency which is
standard for S-band. The general view of the accelerat-
ing system with MW power port is represented in Fig.1.
Structure period was chosen according to the equation
2
pl
⋅β λ ⋅ θ
=
⋅ π
. (1)
Here λ − generator’s wavelength, βp − wave’s phase
relative velocity, θ − operating mode of the structure.
Fig.1. General view of 1.6 cell accelerating system
The photocathode will be arranged in 0.6 cell’s si-
dewall, therefore accelerating field on the sidewall’s
surface must as high as possible. That is the reason of
making half-cells length equal to 0.6 l⋅ . Zero and π
modes are excited in this structure, mode with μ = π
phase shift per cell is the operating mode. The structure
is characterized by the positive normal dispersion. The
recess of the half diaphragm width was made in the
sidewall of full cell in order to calculate the model cor-
rectly. The resonant frequency of the structure was
tuned to the desired value by means of cell radius varia-
tion. Iris profile was made with rounding to eliminate
the possibility of breakdown. This was done to reduce
the electric field in the window’s aperture because of
high-rate accelerating fields in 1.6 cells accelerating
structure that can lead to electrical breakdown. The ratio
of iris window to the wavelength was set to 0.1. This
value is a trade-off between the wish to get maximum
amplitude of accelerating field and except probable
beam loses on the iris. The structure performance was
also increased by rounding of shells edges. The round-
ing radius value was chosen to provide the highest pos-
sible shunt impedance and Q-factor. Dependences of
shunt impedance and Q-factor of 1.6 cell structure are
shown in Figs.2 and 3 respectively.
ISSN 1562-6016. ВАНТ. 2012. №3(79) 54
The structures power input was realized analogous
to BNL Gun I photoinjector [2]. I.e. standard S-band
waveguide with 72×34 mm cross-section was attached
to the full cell through the coupling diaphragm. The
output of high order modes is connected symmetrically
to the RF power input for better coupling and also to
reduce the electromagnetic field asymmetries. Output of
high order modes is designed in form of evanescent
waveguide [3]. Output of high order modes cross-
section matches sizes of coupling diaphragm. Full cell
with RF port and output of high order modes waves
forms the wave converter. The minimal value of power
reflectivity factor from structure back to the supplying
waveguide is the criterion of the wave converter’s tun-
ing.
Fig.2. Dependence of Q factor versus shells blending
radius
Fig.3. Dependence of Rshunt versus shells blending
radius
Fig.4. Accelerating field distribution along 1.6 cell
structure axis
The structure’s cells radiuses tuning was held to
eliminate the misbalance of electromagnetic field mag-
nitudes in cells. The accelerating field magnitude distri-
bution along structure’s longitudinal axis is shown in
Fig.4 with 1 kW of input power. Mean value of struc-
ture’s accelerating field, shunt impedance and Q-factor
were obtained during the structure’s electromagnetic
characteristics investigation. They are shown in Table 1.
3. 3 CELLS AND 2 HALF-CELLS
ACCELERATING STRUCTURE
First considered travelling wave structure is 3 full
cells and 2 half-cells DLW accelerating structure. Half
cells are located at both sides of the structure. The pho-
tocathode will be situated on the sidewall of one of
them. Size of half-cells was chosen 0.5 l⋅ to eliminate
unnecessary reflection of the signal that can appear in
case of 0.6 l⋅ sized half cells and to make structure’s
tuning to the travelling wave mode more precision. The
mode with μ = π/2 phase shift per cell was chosen as the
operating mode because of the high linear shunt imped-
ance rate and maximal frequency separation between
adjacent modes. The iris width, iris window’s radius and
shells edges rounding radius were equal for all modeled
structures to make the comparison of travelling and
standing wave structures more correct.
Since this structure operates at travelling wave mode
the structure must include RF power output. RF input
and output are connected to the half cells. As the half
cells length is shorter than the supplying waveguide’s
smaller side, the power is fed and put out of the struc-
ture through the waveguide transitions. The output of
high order modes is connected symmetrically to the RF
power input and output similarly to the previous struc-
ture. Outputs of high order modes are designed in form
of evanescent waveguide that replicates the power input
and output with width equal to the larger side of cou-
pling diaphragm. The general view of 3 full cells and 2
half-cells accelerating structure is shown in Fig.5.
Fig.5. General view of 3 full cells and 2 half-cells
accelerating system
The accelerating field magnitude distribution along
the longitudinal axis of the structure is shown in Fig.6
with 1 kW of RF power fed to the port.
Fig.6. Accelerating field distribution along 3 full cells
and 2 half-cells structure axis
ISSN 1562-6016. ВАНТ. 2012. №3(79) 55
The structure is tuned to the traveling wave mode.
The accelerating field magnitude in adjacent cells dif-
fers from each other less then 3 % and the phase shift
per each cell is 90 degrees. Mean value of the accelerat-
ing field magnitude in the structure is 103 kV/m.
4. 7 CELLS AND 2 HALF-CELLS
ACCELERATING STRUCTURE
Results listed in Tabl.1 shows that the structure con-
sisting of 3 cells and 2 half-cells appeared unable to
provide the necessary level of accelerating field. That
can be easily explained because the traveling wave
mode have a half of amplitude of RF field achievable
for standing wave. To achieve the necessary energy, the
length of the structure was increased twice and therefore
the system consisting of 7 cells and 2 half cells was
considered (Fig.7).
Fig.7. General view of 7 full cells and 2 half cells
accelerating system
Parameters and design of this structure are identical to
the 3 full cells and 2 half cells structure. All electromag-
netic characteristics of the structure obtained during model-
ing are also listed in Tabl.1. The accelerating field distribu-
tion along of the structures longitudinal axis is shown in
Fig.8 with 1 kW of power fed to the RF power input. The
structure’s tuning to the traveling wave mode was made
analogous to 3 full cells and 2 half cells structure.
Fig.8. Accelerating field distribution along 7 full cells
and 2 half-cells structure axis
5. TRAVELLING WAVE RESONATOR
ACCELERATING STRUCTURE
Next improvement for travelling wave accelerating
system that allows providing of higher level of electro-
magnetic fields is to convert 7 full cells and 2 half-cells
system into travelling wave resonator (TWR). It can be
useful as the short current pulses accelerating structure.
The general view of TWR accelerating system is shown
in Fig.9.
The accelerating system of photoinjector can be de-
signed as the part of TWR ring. The power is fed to the
structure due to the directional coupler. If the length of
the TWR circuit equals the full number of generator
wavelengths, the magnitude of electromagnetic fields in
TWR reaches its maximum and magnitude of the wave
incoming to the load from the ring turns to minimum.
This is similar to the concepts and expressions for the
cavity resonators. The difference is that in the TWR
storage ring the wave is travelling instead of standing
wave in resonators and part of the wave that is not
spread in the ring doesn’t reflect back to generator but
comes to the coupled load. The generator works on the
coupled load all the time indeed. The MW power pulse
compression can be achieved using TWR.
The optimal operation regime of the structure is the
critical mode. In this regime part of RF power is fed into
the accelerating system through the directional coupler
and compensates the power resistance losses in the
resonator’s sidewalls. If the structures reflecting coeffi-
cient αT is insignificant, electrical field magnitude in
storage ring may be many times more than the magni-
tude of feeding wave. It can be noted that the wave
coming to the matched load consists of two waves in the
opposite phases: one from the TWR circuit, another
from the generator.
The directional coupler with narrow or wide side
coupling represents the connection of two waveguides
by coupling windows with space shift of quarter wave-
length between the windows irradiating in the opposite
directions of jointed waveguide. The directional coupler
computation including the receiving of required transfer
coefficient in the forward direction of jointed wave-
guide C simultaneously keeping transfer coefficient in
the opposite direction of jointed waveguide |P| below
the certain level. The directivity coefficient is also sig-
nificant characteristic that is determined by the expres-
sion:
10 lg
| |
C
D
P
= . (2)
Here D is the directivity coefficient of the directional
coupler, C − transfer coefficient in the forward direction
of jointed waveguide, P − transfer coefficient in the
opposite direction of jointed waveguide.
Taking into account part of the signal branching in
the opposite direction and intensity attenuation factor,
expression for the magnitude of electrical field traveling
in TWR storage ring can be written down this way:
124
1
| |1 T
C
b j a
Pe α
= ± −
−
. (3)
Here a1 – RF generator signal intensity magnitude,
αT – TWR ring signal intensity attenuation factor, b4 –
TWR ring electrical field intensity magnitude [4].
The magnitude of wave coming to the coupled load
is not zero for any value of transition coefficient that
differs from 21 Te− α− . The wave is coming from the
ring to the coupled load is summarized in the phase with
wave coming from generator in case of undercoupled
resonator and in opposite phases in case of overcoupled
resonator.
ISSN 1562-6016. ВАНТ. 2012. №3(79) 56
The TWR accelerating system tuning is primarily
consists of connecting power input and output ports of
the system: waveguide bends were attached to the ports.
Waveguide bends were computed to provide minimal
possible reflections on the operating frequency. Reflec-
tion coefficient of modeled waveguide bends is
S11 = -32.8 dB.
Fig.9. General view of TWR accelerating system
The TWR tuning to provide full number of wave-
lengths filling the ring length was made by varying the
distance between waveguide bends and waveguide tran-
sitions. As a result of tuning the length of the TWR fits
five wavelengths.
The structure’s reflection coefficient equals to
S11=1.43 %, the transition coefficient taking into ac-
count power losses in copper sidewalls of the structure
equals to S21=96.1 %. Thus the transition coefficient of
directional coupler must be equal to 3.9 % for the criti-
cal coupling mode of TWR with directional coupler.
Three coupling window model was applied to pro-
vide high directivity level of the directional coupler
(Fig.10). The multiplying of coupling windows number
doesn’t improve to the directivity coefficient. The
waveguide coupling was done by using of the rectangu-
lar coupling windows located on the narrow waveguide
side to eliminate of the possible electrical breakdown of
waveguide due to small window’s sizes. Each coupling
window has corners rounding radius of half spacing
between the waveguides. The transition coefficient of
directional coupler is S41 = C = 3.9 % that equals to the
TWR ring decay coefficient at the 6.5 mm coupling
window width, sidewall width between waveguides is
4 mm. Sidewalls width hasn’t got sufficiently impact to
the directivity coefficient. The transfer coefficient in the
opposite direction of TWR ring equals S31 =P = -53 dB.
Thus the directivity coefficient of the directional cou-
pler is D = 12.4 dB.
Fig.10. Electrical field distribution in directional
coupler
The magnitude of electromagnetic field can be in-
creased three times using TWR comparatively to the
ordinary 7 cells and 2 half-cells accelerating structure
(or necessary RF power can be decreased 9 times) at
given values of the transition coefficient of directional
coupler, the directionality and the decay factor of TWR
ring, under the assumption of equation (3) for the
strength of electromagnetic field in TWR ring. The
mean value of accelerating field magnitude in case of
1 kW input power equals to 321.9 kV/m (Tabl.1).
6. ELECTRON BEAM DYNAMICS
INVESTIGATION
The beam dynamics simulation in designed acceler-
ating structures was done using BEAMDULAC-BL
code designed in research laboratory DINUS of NRNU
MEPhI [5]. The electron beam dynamics can be simu-
lated taking into account the beam loading effect and
Coulomb field influence using this code version. The
simulation was done for beam having typical parameters
for photoinjector: beam pulse charge Q = 0.1 nC, beam
pulse current I = 5 A, injection energy Winj= 10 keV,
beam radius r= 200 μm. The main aim of investigation
was to define the value of acceleration field magnitude
which will provide acceleration of the electron bunch to
the energy of 1 MeV.
Table 1
Main characteristics of the models
Parameters 1.6
cell
3 cells and
2 half-cells
7 cells and
2 half-cells TWR
Operating
mode π π/2 π/2 π/2
Structure
length, mm 77.6 105 210 210
Emean, kV/m
(1 kW input
power)
312.3 103.8 107.3 321.9
Q-factor 16530 9290 10800 10800
Rshunt,
MOhm/m 57.9 49.1 54.9 54.9
Table 2
Results of beam dynamics simulation in designed
models (output beam energy 1 MeV)
Parameters 1.6
cell
3 cells and
2 half-
cells
7 cells and
2 half-cells TWR
0 /E Pλ 1037 345 367 1102
E, MV/m 10.4 9.1 6.5 6.9
P, MW 1.5 20.0 4.0 0.5
Results of beam dynamics investigation shows that
the 1.6 cell DLW structure cam provide electron beam
acceleration to the energy of 1 MeV with 1.5 MW RF
power fed to the system. This result is in the good
agreement with experimental data obtained in accelerat-
ing centers. The accelerating structure based on 3 full
cells and 2 half cells can provide the beam acceleration
to 1 MeV with 10 MW of RF power, 7 full cells and
2 half-cells structure – with 4 MW of RF power. The
TWR accelerating system shows best results – only
500 kW of RF power is necessary.
ISSN 1562-6016. ВАНТ. 2012. №3(79) 57
The beam transverse emittance is shown in Fig.11 in
front end (red) and in output (blue) of TWR structure. It
is clear that beam size preservation can be realized in
accelerator. It should be reminded that the “pencil” and
high brightness beam is necessary for Cherenkov THz
generator.
Fig.11. Transverse emittance of the electron bunch in
the input (red dots) and in the output (blue dots) of the
photoinjector
CONCLUSIONS
Electromagnetic models of ps band photoinjector
were simulated and the analysis of electromagnetic
characteristics of such models was done. It was shown
that the accelerating system based on TWR with 7 cells
and 2 half-cells can provides the accelerating field level
comparable to 1.6 cells standing wave system with close
values of input power. It allows the accelerating field
magnitude decreasing and can decrease the possibility of
electrical breakdown in the system. The electron beam
dynamics analysis shows that the TWR accelerating sys-
tem provides beam acceleration to required energy with
lowest RF power comparatively all other structures and
beam quality preservation can be realized.
REFERENCES
1. A.V. Smirnov. A High Performance, FIR Radiator
Based on a Laser Driven E-Gun, ISBN 978-1-
60456-720-5, 2008.
2. D.T. Palmer, et al. SLAC–PUB–7420, May 1997.
3. A. Anisimov, et al. // Proc. of RuPAC-2010, p.328.
4. J.L. Altman. Microwave circuits. Van Nostrand Co.,
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5. T.V. Bondarenko, et al. // Proc. of HB 2010, p.123.
Статья поступила в редакцию 23.09.2011 г.
УСКОРЯЮЩАЯ СИСТЕМА ФОТОИНЖЕКТОРА ДЛЯ ГЕНЕРАТОРА МОЩНОГО ИЗЛУЧЕНИЯ
ТЕРАГЕРЦОВОГО ДИАПАЗОНА
Т.В. Бондаренко, С.М. Полозов
Для генерации мощного электромагнитного излучения терагерцового диапазона частот может быть ис-
пользована схема, в которой излучение генерируется коротким монохроматическим сгустком электронов,
пролетающим по диэлектрическому или гофрированному капилляру. Короткий сгусток электронов может
быть сгенерирован с использованием фотоинжектора. В работе описывается разработка модели ускоряющей
системы фотоинжектора десятисантиметрового диапазона частот для такого источника и проводится анализ
динамики пучка электронов в такой структуре. Целью работы является разработка оптимальной модели,
обеспечивающей максимальную эффективность и большую величину ускоряющего поля при минимальной
мощности питания. Для этого были рассмотрены варианты ускоряющей системы, основанной на круглом
диафрагмированном волноводе (КДВ) различных конфигураций: 1,6 ячейки КДВ, 3 целых ячейки и 2 полу-
ячейки КДВ. Для рассмотрения возможности увеличения электрической прочности системы и снижения
требований к источнику ВЧ-питания, рассмотрены модели с 7 целыми ячейками и 2 полуячейками КДВ и
модель резонатора бегущей волны с 7 целыми ячейками и 2 полуячейками. Представлены результаты анали-
за электродинамических характеристик резонансных моделей ускоряющих структур и структур с вводами
мощности. Приведены результаты исследования динамики пучка электронов в структурах.
ПРИСКОРЮЮЧА СИСТЕМА ФОТОІНЖЕКТОРА ДЛЯ ГЕНЕРАТОРА ПОТУЖНОГО
ВИПРОМІНЮВАННЯ ТЕРАГЕРЦОВОГО ДІАПАЗОНУ
Т.В. Бондаренко, С.М. Полозов
Для генерації потужного електромагнітного випромінювання терагерцового діапазону частот може бути
використана схема, в якій випромінювання генерується коротким монохроматичним згустком електронів,
які пролітають по діелектричному або гофрованому капіляру. Короткий згусток електронів може бути зге-
нерований з використанням фотоінжектора. У роботі описується розробка моделі прискорюючої системи
фотоінжектора десятисантиметрового діапазону частот для такого джерела і проводиться аналіз динаміки
пучка електронів у такій структурі. Метою роботи є розробка оптимальної моделі, що забезпечує максима-
льну ефективність і велику величину прискорюючого поля при мінімальній потужності живлення. Для цього
були розглянуті варіанти прискорюючої системи, заснованої на круглому діафрагмованому хвилеводі (КДХ)
різних конфігурацій: 1,6 комірки КДХ, 3 цілих комірки та 2 напівкомірки КДХ. Для розгляду можливості
збільшення електричної міцності системи і зниження вимог до джерела ВЧ-живлення, розглянуті моделі з
7 цілими комірками і 2 напівкомірками КДХ і модель резонатора біглої хвилі з 7 цілими комірками і 2 на-
півкомірками. Представлені результати аналізу електродинамічних характеристик резонансних моделей
прискорюючих структур і структур з введеннями потужності. Наведено результати дослідження динаміки
пучка електронів в структурах.
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