Integrated tuning of dielectric elements of accelerating structures
The method based on a longitudinal waveguide dielectric resonance for tuning dielectric elements of slow-wave structure cells is reported. The cells with dielectric disks are tuned by compensating the permittivity spread and technological tolerances through the selection of the dielectric disk width...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Zitieren: | Integrated tuning of dielectric elements of accelerating structures / G.A. Bryzgalov, V.G. Papkovich, N.A. Khizhnyak // Вопросы атомной науки и техники. — 2001. — № 3. — С. 97-98. — Бібліогр.: 5 назв. — англ. |
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irk-123456789-792302015-03-31T03:02:01Z Integrated tuning of dielectric elements of accelerating structures Bryzgalov, G.A. Papkovich, V.G. Khizhnyak, N.A. The method based on a longitudinal waveguide dielectric resonance for tuning dielectric elements of slow-wave structure cells is reported. The cells with dielectric disks are tuned by compensating the permittivity spread and technological tolerances through the selection of the dielectric disk width. The method provides tuning of disks in the cells to accuracy no worse than 0.01 MHz for the general working frequency of the structure. This method is applicable for determining integrated characteristics of dielectric elements (effective permittivities) in microwave devices that can be used, for example, for the development of exit windows for high power microwave flows. 2001 Article Integrated tuning of dielectric elements of accelerating structures / G.A. Bryzgalov, V.G. Papkovich, N.A. Khizhnyak // Вопросы атомной науки и техники. — 2001. — № 3. — С. 97-98. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS numbers: 29.17.+w http://dspace.nbuv.gov.ua/handle/123456789/79230 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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The method based on a longitudinal waveguide dielectric resonance for tuning dielectric elements of slow-wave structure cells is reported. The cells with dielectric disks are tuned by compensating the permittivity spread and technological tolerances through the selection of the dielectric disk width. The method provides tuning of disks in the cells to accuracy no worse than 0.01 MHz for the general working frequency of the structure. This method is applicable for determining integrated characteristics of dielectric elements (effective permittivities) in microwave devices that can be used, for example, for the development of exit windows for high power microwave flows. |
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Article |
| author |
Bryzgalov, G.A. Papkovich, V.G. Khizhnyak, N.A. |
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Bryzgalov, G.A. Papkovich, V.G. Khizhnyak, N.A. Integrated tuning of dielectric elements of accelerating structures Вопросы атомной науки и техники |
| author_facet |
Bryzgalov, G.A. Papkovich, V.G. Khizhnyak, N.A. |
| author_sort |
Bryzgalov, G.A. |
| title |
Integrated tuning of dielectric elements of accelerating structures |
| title_short |
Integrated tuning of dielectric elements of accelerating structures |
| title_full |
Integrated tuning of dielectric elements of accelerating structures |
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Integrated tuning of dielectric elements of accelerating structures |
| title_full_unstemmed |
Integrated tuning of dielectric elements of accelerating structures |
| title_sort |
integrated tuning of dielectric elements of accelerating structures |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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2001 |
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http://dspace.nbuv.gov.ua/handle/123456789/79230 |
| citation_txt |
Integrated tuning of dielectric elements of accelerating structures / G.A. Bryzgalov, V.G. Papkovich, N.A. Khizhnyak // Вопросы атомной науки и техники. — 2001. — № 3. — С. 97-98. — Бібліогр.: 5 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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AT bryzgalovga integratedtuningofdielectricelementsofacceleratingstructures AT papkovichvg integratedtuningofdielectricelementsofacceleratingstructures AT khizhnyakna integratedtuningofdielectricelementsofacceleratingstructures |
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2025-07-06T03:16:52Z |
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2025-07-06T03:16:52Z |
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1836865880464556032 |
| fulltext |
INTEGRATED TUNING OF DIELECTRIC ELEMENTS
OF ACCELERATING STRUCTURES
G.A. Bryzgalov, V.G. Papkovich, N.A. Khizhnyak
NSC KIPT, Kharkov,
Ukraine, 61108, Kharkov, Akademicheskaya, 1
e-mail: papkovich@kipt.kharkov.ua
The method based on a longitudinal waveguide dielectric resonance for tuning dielectric elements of slow-wave
structure cells is reported. The cells with dielectric disks are tuned by compensating the permittivity spread and
technological tolerances through the selection of the dielectric disk width. The method provides tuning of disks in
the cells to accuracy no worse than 0.01 MHz for the general working frequency of the structure. This method is ap-
plicable for determining integrated characteristics of dielectric elements (effective permittivities) in microwave de-
vices that can be used, for example, for the development of exit windows for high power microwave flows.
PACS numbers: 29.17.+w
1 INTRODUCTION
A periodically loaded metal diaphragms - or dielec-
tric disks - waveguide physically represents a set of the
large number of single cells. In case of a metal waveg-
uide the cell can consist of a ring and diaphragm or an
asymmetrical continuous cup with the central aperture.
An internal ring diameter is equal to a waveguide diam-
eter. The coupling aperture is determined by a designed
operating wavelength, its mode and phase velocity un-
der the chosen constant diaphragm thickness. The cell
length is determined by an accelerating structure period.
As a rule an individual tuning of a diaphragmatic
waveguide cell is carried out by selection of the internal
waveguide diameter at a composite resonator model [1].
Cell tuning accuracy by such a method is at a level of
0.1 MHz for the modern electron linear accelerator.
At transition from the periodic waveguide metal
structure to dielectric one in the simplest variant [2]
metal diaphragms are replaced by dielectric rings. Pres-
ence of dielectrics with a relative dielectric permittivity
ε in the cell volume puts a number of specific prob-
lems at the tuning of single cells for the general struc-
ture frequency. It is caused by several factors – dielec-
tric parameters variation throughout the disk volume (a
transit channel presence, inhomogeneity of disk materi-
al) and a choice of a disk thickness as a tuning parame-
ter as a more technological one in the case.
2 TUNING FEATURES OF DIELECTRIC
STRUCTURE ELEMENTS
Dielectric disks for an accelerating structure are
made of separate ceramic slugs. Technological spread
when preparing various parties of slugs (milling initial
ceramics component, temperature condition of baking,
other technological processes) results in the spread of
dielectric permittivity both between single prepared par-
ties of slugs, and inside the single party. Measurements
of dielectric permittivity carried out over test ceramic
disks have shown that a dielectric permittivity spread
between single parties can achieve several units, and in
the disk volume a variation of dielectric permittivity has
been observed up to unit (between central and peripher-
al areas). Measurements of dielectric permittivity are
carried out by a method of resonant electromagnetic
wave scattering on a dielectric sphere into a rectangular
waveguide [3].
Presence of the transit channel along a system axis
results in reduction of dielectric loading in the system. It
should be noted, that unlike the diaphragmatic waveg-
uide the transit channel radius 0r in a dielectric struc-
ture can be prescribed arbitrary. As a rule, it gets out
proceeding from two main conditions: 20 gr λ< and
20 br < , where gλ is the wavelength in a waveg-
uide, b is the dielectric disk thickness.
For operating at a 10 cm wave band the characteris-
tic dimensions of dielectric disks with 90=ε (titanium
dioxide ceramics) are: the external disk diameter ~ 80
mm, the transit aperture diameter ~ 5 mm, the disk
thickness ~ 2,7 mm at a wave phase velocity in the
structure 1== cvphphβ .
A tuning of dielectric disks for working frequency is
carried out by a resonant method. A phenomenon
waveguide-dielectric resonance (WDR) is known to be
observed in a single dielectric sample placed into an
evanescent waveguide on condition that
( )1
12
+
+=
εε
ε
cres ff , (1)
where cf is the critical frequency of a hollow waveg-
uide, [4]. In a waveguide periodically loaded with di-
electric disks a phenomenon of longitudinal waveguide-
dielectric resonance (LWDR) is observed under a wave
phase shift between adjacent disks 2πψ = [5]. We
can tune dielectric disks for the given frequency cf by
selection of their thickness, having a predetermined re-
quired waveguide radius
c
c f
cR
π
σ
2
0= from the condi-
tion of the resonance (1), where c is the light velocity,
and 0σ is the first root of Bessel's function of the zero
order.
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 97-98.
97
The behavior of dispersive curves for the loaded di-
electric disks waveguide is shown in Fig. 1 at the vari-
ous periods of disks arrangement (1-L = 8 mm; 2 - 15
mm; 3 - 27 mm).
2 7 6 0 2 8 0 0 2 8 4 0
- 0 . 8
0
0 . 8
f , M H z
co
s ψ
b < b
r e s
b = b
r e s
b > b
r e s
1
2
3
1
2
3
1
2
3
Fig. 1.
The initial resonant thickness of dielectric disks is
estimated by loading the waveguide with solid disks
2 1
4 1
eff
res
eff res eff
cb
f
ε
ε ε
+
=
−
, (2)
where
2
011 ln( )
2eff
r
R
ε ε ε
= −
is the effective
dielectric permittivity of disks taking into account the
central channel.
l/2 l/2
Phaser Recording unitGenerator
2R
b
Fig. 2.
A schematic diagram of dielectric disks tuning setup
is shown in Fig. 2. The dielectric disk in a metal holder
is placed into a circle evanescent waveguide consisting
from two identical sections in length / 2l . In the sys-
tem the mode 01E is excited with the help of probes.
The wave, reradiated by a disk, excites a probe of a
transducer signal that is detected, amplified and regis-
tered. Waveguide section lengths are selected such that
the reflectings from the ends of the system were mini-
mum. In our case the influence of opened section ends
at the disk resonance frequency did not exceed ±
0.03 MHz at the total length l = 1200 mm. The mea-
surement of frequency is carried out with the help of a
carrier of frequency and electronic-countable frequency
counter. Accuracy of manufacturing the waveguides and
a disk diameter is in limits ±0.01 mm, for a disk thick-
ness of ±0.002 mm. The system temperature is support-
ed to be constant during measurements.
The results of the experimental studying the dispers-
ing characteristics of a loaded identical dielectric disk
structure are shown in Fig. 3 depending on the period of
their arrangement (disk resonance frequency is
1 - resf = 2799.00 MHz; 2 - 2798.27 MHz;
3 - 2797.99 MHz; 4 - 2796.80 MHz).
8 1 2 1 6 2 0 2 4
2 7 8 0
2 8 0 0
2 8 2 0
2 8 4 0
L , m m
f,
M
H
z
1
2
3
4
Fig. 3.
A resonance frequency of the mode 01E was evalu-
ated taking into account the effective dielectric permit-
tivity for a multielement system (2800 MHz) that corre-
sponds to the experimental results obtained.
The developed method of tuning dielectric disks has
allowed rather promptly and with a big accuracy to tune
dielectric structure cells for the given frequency. Be-
sides also the inverse problem is solved easily - at the
known LWDR frequency and the disk thickness it is
possible to determine a material effective dielectric per-
mittivity value. The method can find application also for
tuning the dielectric window output for powerful mi-
crowave sources.
REFERENCES
1. O.A.Val'dner, N.P.Sobenin, B.V.Zverev,
I.S.Shchedrin. The reference book on diaphragmat-
ic waveguides. M.: Atomizdat. 1977, 376 p. (in
Russian).
2. Ya.B.Fainberg, N.A.Khizhnyak. Artificial
anisotropic media // ZTF. 1955, v. 25, #4, p. 711-
719 (in Russian).
3. N.A.Khizhnyak. The integrated equations of
macroscopical electrodynamics. Kiev: "Naukova
Dymka", 1986 (in Russian).
4. V.A.Korobkin, N.A.Khizhnyak. A waveguide-di-
electric resonance of a dielectric sample in a rectan-
gular waveguide // Izv. VUZov. Radiophysics. 1978,
v. 21, # 4, p. 558-565 (in Russian).
5. V.G.Papkovich, G.A.Bryzgalov, N.A.Khizhnyak. A
longitudinal waveguide-dielectric resonance in sys-
tems with artificial anisotropic loading // ZTF.
1980, v. 50, # 2, p. 409-410 (in Russian).
98
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