Main systems development of K-band linac
The main purpose of our work is the creation of the small-sized linear electron accelerator on the energy up to 5 MeV on the base of such low-power Х- and K-bands sources. In this paper the results on development of main systems for such an accelerator are represented: two versions of an injector sy...
Збережено в:
| Опубліковано в: : | Вопросы атомной науки и техники |
|---|---|
| Дата: | 1999 |
| Автори: | , , , , , , |
| Мова: | Англійська |
| Опубліковано: |
1999
|
| Онлайн доступ: | https://nasplib.isofts.kiev.ua/handle/123456789/81144 |
| 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: | Main systems development of K-band linac / M.I. Ayzatsky, E.Z. Biller, A.N. Dovbnya, V.A. Kushnir, V.V. Mitrochenko, S.A. Perezhogin, I.V. Khodak // Вопросы атомной науки и техники. — 1999. — № 3. — С. 26-28. — Бібліогр.: 14 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860148611744006144 |
|---|---|
| author | Ayzatsky, M.I. Biller, E.Z. Dovbnya, A.N. Kushnir, V.A. Mitrochenko, V.V. Perezhogin, S.A. Khodak, I.V. |
| author_facet | Ayzatsky, M.I. Biller, E.Z. Dovbnya, A.N. Kushnir, V.A. Mitrochenko, V.V. Perezhogin, S.A. Khodak, I.V. |
| citation_txt | Main systems development of K-band linac / M.I. Ayzatsky, E.Z. Biller, A.N. Dovbnya, V.A. Kushnir, V.V. Mitrochenko, S.A. Perezhogin, I.V. Khodak // Вопросы атомной науки и техники. — 1999. — № 3. — С. 26-28. — Бібліогр.: 14 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | The main purpose of our work is the creation of the small-sized linear electron accelerator on the energy up to 5 MeV on the base of such low-power Х- and K-bands sources. In this paper the results on development of main systems for such an accelerator are represented: two versions of an injector system and accelerating section. The operating frequency of the accelerator is 12500 MHz.
|
| first_indexed | 2025-12-07T17:51:23Z |
| fulltext |
MAIN SYSTEMS DEVELOPMENT OF K-BAND LINAC
M.I. Ayzatsky, E.Z.Biller, A.N.Dovbnya, V.A.Kushnir, V.V.Mitrochenko, S.A.Perezhogin,
I.V.Khodak
NSC KIPT, Kharkov, Ukraine
INTRODUCTION
Nowadays the majority of radiation technologies
for both industrial and medical purposes is based on the
use of electron beams with energies Е=1÷10 MeV and
average power Р>0.5 kW. The beam acceleration up to
such energies with operating performances, accepted to
applied application, mainly is realized in resonance
accelerators, in which the energy from an external
microwave source is transformed to the energy of
electrons. A microwave oscillations of L- and S-bands
were widely used till now, though the number of
development on the use of X-band was conducted in the
80-ies as well [1-3]. However, numerous science-
research jobs and experimental-constructive jobs,
carried out now in many science centers in order to
develop future linear colliders, have again attracted
attention of the developers of the applied accelerating
equipment to the X-band oscillations [4, 5]. As until
recently this range was poorly used in accelerating
equipment, the number of the most acceptable RF-
sources (Р=1-2 MW) for use in applied accelerators of
X-band is limited (1.5 MW a magnetron PM-1100X and
some devices in development [5]). However, there are a
number of sources with a smaller output pulse power,
which were already used in accelerators, [1] or were
developed for other applications.
The main purpose of our work is the creation of
the small-sized linear electron accelerator on the energy
up to 5 MeV on the base of such low-power Х- and K-
bands sources. In this paper the results on development
of main systems for such an accelerator are represented:
two versions of an injector system and accelerating
section. The operating frequency of the accelerator is
12500 MHz.
TRADITIONAL INJECTOR SYSTEM
In this section the traditional type of injector
system’s version is considered. The injector consists of
an electron source [6], buncher and accelerating
resonance RF system. It was supposed that the initial
electron energy makes 25 keV and the power of a
microwave feed source is 100 kW. The injector system
of an S-band accelerator KUТ [7] containing one
bunching and one accelerating resonator was accepted
as a prototype. On the base of simulations and analysis
we have carried out the cylindrical resonator was
selected as a buncher. At the input power of 107 W and
the beam current of 50 mA the bunch phase length 40°
is ensured on a distance 1.8 cm from the center of a
resonator.
On the smaller working wave lengths at the
limited microwave feed power and low injection energy
for maintenance of effective capture of particles in the
process of acceleration it is necessary to use an
accelerating system consisting of several resonators. By
the experience of developing the resonance structure for
injector systems [8], the lengths of the first and second
accelerating resonators and the field strength in them
were selected to provide the intense phase particle
movement that is necessary for an effective bunching.
The main increase of energy is carried out in consequent
resonators. In the result of multiple calculations of
particle dynamics and distribution of an accelerating
field we selected a variant of an accelerating part of
three resonators with π - mode (see Fig. 1). The Q-
factor of such a system is 6200. The average field in
resonators appropriating to the input power 100 kW is
25.4 MV/m.
Fig. 1 Injector accelerating system.
3
The simulation of electron dynamics was done
with using the PARMELA code [9]. At the input power
100 kW the maximum electron energy is 480 keV. For
this the energy spectrum width is ∆W/W=30 %, and the
phase one is ∆ϕ=23°. The beam normalized emittance
increasing because of its interaction with the field of a
buncher and accelerating system does not exceed ε
rms = 3.3⋅π⋅mm⋅mrad, and the maximum value of capture
coefficient is 96 %.
According to simulations the input power variation
within ±10-20 % relating to the initial one does not
render essential influence on the normalized beam
emittance. Its relative variation is only 10 %. The input
power increasing within the limits of 10-15 % leads to
the improvement of the spectral beam characteristic
obtained. So, at the value of an input power 120 KW it
is possible to receive the beam energy spectrum width ∆
W/W=15 %, and the phase one ∆ϕ=23°. At this point,
accordingly, the total energy gained by the beam will
increase. In this case, it will be 530 keV that
corresponds to a beam phase velocity βф = 0.87 с.
RF-GUN
In this section the possibility of the RF-gun with
the thermionic cathode [10] using as an accelerator
injector system is considered.
The resonance system was calculated in two
stages. The RF-gun resonator geometry was optimized
at the first stage. The purpose of optimization was the
obtaining such an axial electrical field distribution at
which the beam characteristics would satisfy the
declared requests. On the other hand, the geometry of
resonators would satisfy the technological possibilities
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 1999. №3.
Серия: Ядерно-физические исследования (34), с. 26-28.
26
of their manufacturing. At the second stage for the
selected gun geometry the large amount of calculations
was conducted for various maximum values of the
accelerating field intensity in a gun Еmax, for various
ratios of maximum intensity of accelerating fields in
resonators. At the same time, it is necessary to take into
account some features when calculating the RF-guns
with a thermoionic cathode. The most important of them
is the effect of cathode back bombardment [10].
The electron beam on the RF-gun exit should be
with a low emittance, the electron energy approximately
of 0.5 MeV, and the energy and phase spectrum width
not exceeding 40 % and 60°, respectively. For
maintenance of the required energy the resonator system
should consist of several resonators. Length of the first
resonator and the field strength ensure the delivery of an
innumerable electron quantity emitted from the cathode
to the second resonator input. The second resonator
ensures the grouping of particles. The main energy gain
should take place in consequent resonators. Such a RF-
gun construction allows to provide the beam grouping
sufficient for injection in the accelerating section.
As a result of purposeful searches the axial
electrical field distribution which satisfies the stated
above principles was found for the resonance system
consisting of three accelerating resonators. The RF-gun
resonance system geometry and the field distribution are
represented in Fig.2.
Fig. 2. The RF-gun resonance system geometry.
The Q-factor of the resonance system is 5300,
shunt impedance 139 MOh/m. The calculated beam
characteristics on the gun exit are represented in table 1.
Table 1
Р (kW) 100 120 150 200 250 300
εx (mm mrad) 2.64 3.05 2.85 2.83 3.09 3.19
Breadth of an energy spectrum
(∆W/W) , % 45 50 32 36 36 39
∆ϕ, deg. 50 56 51 47 44 41
Maximum energy (keV) 408 442 489 554 610 660
Average energy (keV) 330 364 408 461 506 541
Capture coefficient (%) 60 62.8 66 70.7 73.6 76
DEVELOPMENT OF THE 12.5 GHz
ACCELERATING SECTION
The preliminary characteristics and dimensions of
cells of the 12.5 GHz accelerating section with a 2π/3-
oscillation mode are calculated by the data given in
[11]. Hereafter for a determination of more accurate
sizes, special codes developed for these purposes were
used [12, 13]. Some sizes: diaphragm thickness t=1 mm,
orifice in the diaphragm 2a=6 mm, rounding radii of
orifices in the diaphragm 0.5 mm were selected on the
technological reasons. The 12.5 GHz structure period on
a 2π/3- oscillation mode is D = 7.994 mm. The cell
diameter 2b was calculated with using the SUPERFISH
code: at f=12500.0 MHz, b=9.5163 mm. Using the
codes developed on the base of the method partial areas
[12] the main electrodynamic parameters of disk-loaded
waveguide were obtained:
- shunt impedance R=117 Ohm/m
- group velocity b=0.021
- damping factor a=0.9 m-1.
The calculation results were used for
manufacturing the experimental accelerating cells. The
main problem at this point was improvement of the
process, methods of tuning and microwave
measurements. The measurements of cells have shown
that the frequencies of single resonators are close to the
preset values. The measurements of a resonance model
from five whole- and two semi-rings were conducted. In
such resonance model the frequencies appropriate to
seven types of oscillations were defined. With using the
SUPERFISH code the dispersion curve of such a
resonance model was calculated.
12200
12250
12300
12350
12400
12450
12500
12550
12600
12650
0 30 60 90 120 150 180
θ , °
f, M
Hz
SU PE RFISH
E xperim e nt
Fig. 3
Fig. 3 represents a dispersion curve designed by
the SUPERFISH code (solid) and dispersion curve
experimentally measured for the present resonance
breadboard model (dash).
The experimentally measured Q-factor is about
1500 that approximately four times less than the
calculated one. Such divergence is explained by a poor
quality of contacts.
At the following stage the trial soldering of a
model consisting of two rings and two semi-rings was
carried out. The measurements have shown that the
soldering leads to displacement of mode frequencies at
35 MHz. The Q-factor of a soldered model was
increased and was on a working mode 2500. The
influence of soldering on the frequency was simulated
with the SUPERFISH code by introduction of rounding
radius in a place appropriate to the meniscus of the
solder. It was established that the displacement at
35 MHz corresponds to the rounding radius of 0.6 mm.
For precise frequency tuning of cells the four
tuning orifices are made in rings which enable to
increase the frequency up to 40 MHz. As a result of
measurements the possibility of a resonance model
tuning is established to within several tens kilohertz.
The data obtained were used for manufacturing an
experimental sample of homogeneous accelerating
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 1999. №3.
Серия: Ядерно-физические исследования (34), с. 26-28.
26
section consisting of 21 cells. During manufacturing the
section the tuning of cells was performed in a special
resonance model [14].
We carried out the simulation of particle dynamics
in different variants of 12.5 GHz accelerating sections
with the use of the PARMELA code [9]. It was
determined that for sections with βф=1 at a microwave
feed power of 0.5-1.0 MW the energy of electron
injection should exceed 1 MeV. The simulation results
are represented in Table 2. Parameters of the electron
beam at the input are the following: Winj=1.0 MeV, ∆ϕ
=300, (∆W/W)rms=3.7 %, I=50 mA, L=56.8 cm - length
of accelerating section.
Table 2
Рinj(MW) Wavr(MeV) (∆W/W)rms ∆ϕ ° Erms x, mm⋅
mrad
0.5 5.10 1,81 % 15 1.26
1.0 7.03 0.93 % 20 1.24
Taking into account that the particle energy at the
injector system exit being in question is 0.3÷0.5 MeV
we have considered a variant of accelerating section
with a variable phase velocity. It consists of different
phase velocity parts: 0.8с, 0.85с, 0.9с, 0.92с, 1с. The
simulation was carried out with the following beam
parameters at the section input: Winj=0.34 MeV, ∆ϕ
=300, (∆W/W)rms=7.4 %, I=50 mA. The length of the
section is L=65 cm. At the input power 0.5 MW the
following results are obtained: Wmax=4.47 MeV, (∆
W/W)rms= 4.15%, ∆ϕ = 220, εrms x =1.13 mm⋅mrad.
CONCLUSIONS
The systems of the K-band accelerator we have
developed allow to obtain the high-quality beams at a
rather small (up to 0.5 MW) RF-feed power. Both
considered schemes of injectors under cosideration can
be used. At the same time, it is necessary to note that for
the high quality of the electron source the use of a
traditional scheme is preferable. The technological
methods of manufacturing and technique of tuning of an
accelerating structure are developed. All this allows to
begin the creation of the operative experimental K-band
accelerator.
REFERENCES
1. I.S. Schedrin Three-centimetric band linear electron
accelerators. // VANT, Series: Technique of
physics experiment, 1985, vol.2 (23), p.71-75.(in
Russian)
2. R.G.Schonberg et al. // Portable, X-band Linear
Accelerator System. IEEE Trans., 1985, NS-32,
No.5, pp.3224-3236.
3. E.Tanable et al. A Small Diameter Standing Wave
Linear Accelerator Structure. // IEEE Trans., 1985,
NS-32, No.5, pp.2975-2977.
4. Sun Xiang et al. A portable X-band On-axis Standing
Wave Linac Structure.// Proceedings of the PAC97,
1997, v.1, p.1221-1223.
5. S.M.Hanna. Application of X-band Technology in
Medical Accelerators.//Proceedings of the PAC99,
1999, v.5, p.2516-2518.
6. V.I. Beloglasov, E.Z. Biller, V.A. Vishnýakov et. al.
Electron Guns for Technological Linear
Accelerators // Problems of Atomic Science and
Techn. 1999. v. 4. Issue: Nuclear Physics
Researches, (35), p. 29.
7. M.I. Ayzatsky , V.I.Beloglazov, V.N.Boriskin et al.
// Proc. of the SOURCES’94, p.409-413
8. O.А. Valdner, А.D. Vlasov, А.V. Shalnov Linear
Accelerators. - М.: Atomizdat, 1969.-p.247.
9. PARMELA, Lloyd M. Young, Los Alamos
National Laboratory, Preprint LA-UR-96-1835
10. V.A. Kushnir, High-Frequency Electron
Guns - Current Status // Problems of Atomic
Science and Techn. 1999. v. 3. Issue: Nuclear
Physics Researches. (34), p. .
11. O.A. Valdner, N.P. Sobenin, B.V. Zverev,
I.S. Schedrin Spravochnic on diafragmirovanym
volnovodam. Izd. 2, М.: Atomizdat, 1977.
12. V.I. Naydenko, E.V. Guseva // R&E. 1987, v.32,
№8, p.1735-1757.
13. J.H. Billen, L.M. Young // Proceedings of the 1993
Particle Accelerator Conference, Vol.2. of 5.
790 -792 (1993).
14. M.I.Ayzatsky , E.Z.Biller Development of
Inhomogeneous Disk-Loaded Accelerating
Waweguides and RF-coupling // Proceedings of the
XVIII International Linear Accelerator Conference,
Geneva, 1996, v.1, p.119-121.
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 1999. №3.
Серия: Ядерно-физические исследования (34), с. 26-28.
26
INTRODUCTION
CONCLUSIONS
REFERENCES
|
| id | nasplib_isofts_kiev_ua-123456789-81144 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| language | English |
| last_indexed | 2025-12-07T17:51:23Z |
| publishDate | 1999 |
| record_format | dspace |
| spelling | Ayzatsky, M.I. Biller, E.Z. Dovbnya, A.N. Kushnir, V.A. Mitrochenko, V.V. Perezhogin, S.A. Khodak, I.V. 2015-05-11T17:58:50Z 2015-05-11T17:58:50Z 1999 Main systems development of K-band linac / M.I. Ayzatsky, E.Z. Biller, A.N. Dovbnya, V.A. Kushnir, V.V. Mitrochenko, S.A. Perezhogin, I.V. Khodak // Вопросы атомной науки и техники. — 1999. — № 3. — С. 26-28. — Бібліогр.: 14 назв. — англ. https://nasplib.isofts.kiev.ua/handle/123456789/81144 The main purpose of our work is the creation of the small-sized linear electron accelerator on the energy up to 5 MeV on the base of such low-power Х- and K-bands sources. In this paper the results on development of main systems for such an accelerator are represented: two versions of an injector system and accelerating section. The operating frequency of the accelerator is 12500 MHz. en Вопросы атомной науки и техники Main systems development of K-band linac Pазработка основных систем линейного ускорителя электронов сантиметрового диапазона published earlier |
| spellingShingle | Main systems development of K-band linac Ayzatsky, M.I. Biller, E.Z. Dovbnya, A.N. Kushnir, V.A. Mitrochenko, V.V. Perezhogin, S.A. Khodak, I.V. |
| title | Main systems development of K-band linac |
| title_alt | Pазработка основных систем линейного ускорителя электронов сантиметрового диапазона |
| title_full | Main systems development of K-band linac |
| title_fullStr | Main systems development of K-band linac |
| title_full_unstemmed | Main systems development of K-band linac |
| title_short | Main systems development of K-band linac |
| title_sort | main systems development of k-band linac |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/81144 |
| work_keys_str_mv | AT ayzatskymi mainsystemsdevelopmentofkbandlinac AT billerez mainsystemsdevelopmentofkbandlinac AT dovbnyaan mainsystemsdevelopmentofkbandlinac AT kushnirva mainsystemsdevelopmentofkbandlinac AT mitrochenkovv mainsystemsdevelopmentofkbandlinac AT perezhoginsa mainsystemsdevelopmentofkbandlinac AT khodakiv mainsystemsdevelopmentofkbandlinac AT ayzatskymi pazrabotkaosnovnyhsistemlineinogouskoritelâélektronovsantimetrovogodiapazona AT billerez pazrabotkaosnovnyhsistemlineinogouskoritelâélektronovsantimetrovogodiapazona AT dovbnyaan pazrabotkaosnovnyhsistemlineinogouskoritelâélektronovsantimetrovogodiapazona AT kushnirva pazrabotkaosnovnyhsistemlineinogouskoritelâélektronovsantimetrovogodiapazona AT mitrochenkovv pazrabotkaosnovnyhsistemlineinogouskoritelâélektronovsantimetrovogodiapazona AT perezhoginsa pazrabotkaosnovnyhsistemlineinogouskoritelâélektronovsantimetrovogodiapazona AT khodakiv pazrabotkaosnovnyhsistemlineinogouskoritelâélektronovsantimetrovogodiapazona |