Investigation of surface resistance OF Al, Be AND Al-Be alloy at low temperatures
Our work contains experimental and theoretical studies on the surface resistance of aluminium A999, A99 as a function of annealing temperature, frequency of electromagnetic oscillations, cooling temperature and processing technology. Results of investigation of Al-Be alloy surface resistance in a wi...
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| Date: | 2000 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2000
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| Cite this: | Investigation of surface resistance OF Al, Be AND Al-Be alloy at low temperatures / V.M. Azhazha, K.V. Kovtun, V.A. Kutovoj, N.A. Khizhnyak // Вопросы атомной науки и техники. — 2000. — № 2. — С. 94-96. — Бібліогр.: 6 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860014817117470720 |
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| author | Azhazha, V.M. Kovtun, K.V. Kutovoj, V.A. Khizhnyak, N.A. |
| author_facet | Azhazha, V.M. Kovtun, K.V. Kutovoj, V.A. Khizhnyak, N.A. |
| citation_txt | Investigation of surface resistance OF Al, Be AND Al-Be alloy at low temperatures / V.M. Azhazha, K.V. Kovtun, V.A. Kutovoj, N.A. Khizhnyak // Вопросы атомной науки и техники. — 2000. — № 2. — С. 94-96. — Бібліогр.: 6 назв. — англ. |
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| container_title | Вопросы атомной науки и техники |
| description | Our work contains experimental and theoretical studies on the surface resistance of aluminium A999, A99 as a function of annealing temperature, frequency of electromagnetic oscillations, cooling temperature and processing technology. Results of investigation of Al-Be alloy surface resistance in a wide range of low temperatures are presented. The technology of the alloy production and treatment for getting the surface resistance lower then that of initial materials (Al, Be) is described. As we have found, this parameter remains to be a constant in a wide range of low temperatures.
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INVESTIGATION OF SURFACE RESISTANCE OF Al, Be AND Al-Be
ALLOY AT LOW TEMPERATURES
V.M. Azhazha, K.V. Kovtun, V.A. Kutovoj, N.A. Khizhnyak
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
Our work contains experimental and theoretical studies on the surface resistance of aluminium A999, A99 as a
function of annealing temperature, frequency of electromagnetic oscillations, cooling temperature and processing
technology. Results of investigation of Al-Be alloy surface resistance in a wide range of low temperatures are
presented. The technology of the alloy production and treatment for getting the surface resistance lower then that of
initial materials (Al, Be) is described. As we have found, this parameter remains to be a constant in a wide range of
low temperatures.
PACS: 74.72.LW; 71.20.Cf
INTRODUCTION
In the process of development and construction of
cryogenic accelerators the important problem is
reaching a high efficiency of the accelerating structure
of accelerator at T>4.2 K without applying the
superconductivity and with the use of nonsupe-
rconducting metals. For example, if in a warm variant it
is permissible to transform 50% of HF oscillations of
energy into the energy of accelerated beam, and if due to
using some technological methods the quality factor of
the accelerating system can be increased at least by one
order of magnitude then the efficiency of energy
transform will be not 50% but 90%. And, since this
effect will require much simpler efforts than in the case
of developing the superconducting accelerator, the final
end will be achieved.
In this connection one is interesting in studies on the
surface resistance of nonsuperconducting metals at
cryogenic temperatures. First of all it is due to that some
nonsuperconducting metals have a high electrical con-
ductivity at low temperatures that determines a possi-
bility of practical use of accelerators in a cold variant.
While developing the cryogenic HF-systems it is
necessary to analyze the coefficient of gain, η, obtained
by the surface resistance of nonsuperconducting metals
(equal to the ratio between the surface resistance at
room temperature and the surface resistance at low
temperatures), depending on cooling temperature,
frequence of electromagnetic field, treatment process,
material composition.
In this work we performed quite a complex of
theoretical and experimental investigations of
superconducting metals in a wide temperature range in
order to determine which of metals has minimum losses
of HF-power and how many times the quality factor of
the accelerating structure of accelerator is increased as
compared to the accelerating structure operating at room
temperature.
MEASUREMENTS
As is known, in the region of classical skin-effect the
surface resistance for nonsuperconducting metals is
determined from the expression
Rk= ( σ
ω µ
2 )1/2
, (1)
where Rk is the surface resistance of nonsuperconducting
metal in the region of classical skin-effect, Ohm; ω is the
angular frequency of electromagnetic oscillations, rad/s;
µ is the magnetic conductivity in vacuum, G/m; σ is the
specific conductivity of normal metal at constant
current, Cm/m.
In the region of abnormal skin-effect the surface
resistance of nonsuperconducting metal is determined
from the expression
Ra=(
1
b )1|3(
l
σ )1|2(
ω µ
2 )2|3
, (2)
where b is the coefficient characterizing the reflection of
conduction electrons from the conductor surface; l is the
length of electron free path.
The coefficient of gain,η, is determined from the
expression
η=
1
13 2 26
ω σ
σ
µ( ) ( )
b
l . (3)
Table 1
R.103 , Ohm T, η F, Hz δ, µm
4,0
0,26
293
4,2
15,4 0,15 6,74
0,43
17,0
1,8
293
4,2
9,4 3,0 1,54
0,16
24,0
2,7
293
4,2
8,9 5,0 1,14
0,13
In Table 1 the results of calculation for aluminium in
the region of classical abnormal skin-effect at
frequencies 0.15 GHz, 3.0 GHz, 5.0 Ghz are given, the
coefficient of gain η by the surface resistance, and the
94 ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2000, № 2.
Серия: Ядерно-физические исследования (36), с. 94-96.
depth of penetration of high-frequency field into metal δ
, for the case of mirror reflection of electrons from the
surface are determined. The calculation results show that
the coefficient of gain by the surface resistance and the
depth of electromagnetic field penetration into metal
decrease with increasing frequency.
To confirm the theoretical results on the surface
resistance we performed a set of investigations in a wide
temperature range on nonsuperconducting metals e.g.
A999, A99, A95 aluminium, aluminium-beryllium alloy
containing 65 wt% berryllium of commercial purity and
3.5 wt% A95 aluminium and beryllium to determine
their dissipative characteristics and to give
recommendations on possibility to use nonsupercon-
ducting metals for manufacturing the resonant HF-
systems of high-quality operating in the field of low
temperatures. To measure the surface resistance at a
frequency of 0.15 GHz we used a toroidal resonator, of
TEM wave type, and at a frequency of 5 Ghz we used a
cylindrical resonator, of H111 wave type, with the height
equal to its diameter. The latter was manufactured on the
turning lathe with subsequent polishing and annealing.
By measuring the self- quality factor of such a resonator
one can to calculate the surface resistance of resonator
material from the expression R=G/Q, where Q is the
self-quality factor of the resonator; G is the geometrical
factor depending only on the resonator size and on the
type of oscillations in it, R is the surface resistance of
material.
The high accuracy of measurements of the surface
resistance R in a wide range of temperatures, from 293
to 4.2K imposes certain requirements on the design of a
resonator the configuration and dimensions of which
should be selected so that high-frequency currents of
oscillation type under consideration were flowing along
the inner side of the resonator without crossing the
mechanical joints in the construction. The absence of
losses in contacts decreases the measurement error. On
cooling the resonator in the frequency band of dominant
oscillation mode, the neighboring EO1O, EO11 oscillations
modes appear that leads to the error in measurements of
the resonator quality factor, besides, the shape of a
resonance curve of dominant oscillation mode in the
measuring resonator takes the distorted view. In this
connection, we developed the methods of suppressing
the neighboring oscillation modes to the dominant one
based on the well-known method of resonator
perturbation induced by metallic needles [2]. For
measurement of the quality factor of the resonator
having the 103 order of magnitude we used the
resonance method [3]. The quality factor of 104 and
higher was measured by the method of damping
decrement [4].
When measuring the surface resistance of metals the
most interest is the self-quality factor of a resonator
being defined with taking into account the energy loss at
the resonator only. In real facilities any resonator is
connected with the outer electric circuits by a feeder, so
the energy loss occurs not only in the same resonator,
but in the outer circuits, too. To exclude the influence of
the outer circuits on the self-quality factor of the
resonator the latter was linked with the generator and the
indicator using a special probe that was designed as a
movable coaxial line with a connection loop situated out
of the resonator. The connection loop was shifted inside
the round wave conductor connected with the resonator.
A high-frequency amplifier was used to provide gaining
of the output HF-power coming from the resonator to a
level sufficient to use the connection of the resonator
with the input- and output HF lead-in via the above-
mentioned probe. The non-linear characteristics of the
measuring HF section including the amplifier, detecting
device and indicator were determined as a function of
HF power to find a region where one can measure the
temperature dependence of the self-quality factor of a
resonator at the same HF power.
The high-frequency investigations of the surface
resistance of A999 and A99 aluminium have shown that,
depending on the cooling temperature, electromagnetic
field frequency, annealing, the lowest surface resistance
can be obtained on the A990 aluminium after polishing
(P) and annealing (A) at frequencies of f≤0.15MHz
(Table 2). At a room temperature the difference in the
surface resistance of aluminum of mentioned type is
practically absent. The surface resistance of A999 and
A99 aluminium at T=4.2 K is 1.2 times higher than that
of A95 aluminium. It is due to the alloying composition.
Table 2
Material R⋅
103,Oh
m
T,
K
η F,
GHz
Treat-
ment
Al A999 4,6
0,39
293
4,2
11,
8
0,15 P+A
Al A999 21,0
3,0
293
4,2
7,0 3,0 P+A
Al A999 27,0
4,2
293
4,2
6,4 5,0 P+A
Al A99 21,0
3,6
293
4,2
5,8 3,0 P+A
Al A99 21,0
4,3
293
4,2
4,9 3,0 P
Fig. 1. The relative surface resistance vs temperature
for aluminium of different types.
95
Fig. 1 shows the relative change of the surface
resistance as a function of the cooling temperature of
A999 and A99 aluminium annealed (curve 1,2) and not
unannealed (curve 3), the frequency of 3GHz. The
investigations performed demonstrated that with the
temperature increasing the surface resistance of A99
aluminium decreases much rapidly than that of A99
aluminium. For A99 aluminium the surface resistance
reaches a maximum value at T=34K (curve 2), and for
A999 aluminium the surface resistance changes up to
the temperature of 4.2K (curve 1). The coefficient of
gain η for annealed A99 aluminium is by 18% higher
than that of unannealed aluminium.
In Table 3 the results of measurements of the surface
resistance at a frequency of 5.0 GHz for aluminium-
beryllium alloy, A95 aluminium after turning work
(TW), polishing (P) and annealing (A) are presented.
As follows from the experimental results in the range
of low temperatures the AL-Be alloy has a surface
resistance less than that of starting components (Al, Be)
and stays constant in the wide range of temperatures
from 50 to 4.2 K (Fig. 2, curve 1).
Fig. 2. The relative surface resistance vs temperature
for Al-Be and Al, Be (curves 1-3, respectively).
Table 3
Material R.103
,
Ohm
T, K η1 η2 Treat-
ment
Al-Be 44,0
11,0
8,6
293
77,3
4,2
4,4 5,1 TW+P
+A
Be 110,0
52,0
50,0
293
77,3
4,2
2,1 2,2 TW+P
+A
Al A95 32,0
13,0
7,1
293
77,3
4,2
2,5 4,5 TW+P
+A
For aluminium the coefficient of gain reaches its
maximum value at a temperature of T=35K (curve 3)
and for beryllium T=70K (curve 3).
CONCLUSION
For the Al-Be alloy the coefficient of linear
expansion is invariable in a wide range of low tempera-
tures and therefore this alloy can be successfully applied
as a structural material for manufacturing the compo-
nents of accelerating structures of the accelerator
operating in a wide range of temperatures from 50 to
4.2K So, to attain the optimum parameters of HF-
systems in the range of cryogenic temperatures, i.e. to
increase appreciably the quality factor for decreasing the
losses of high-frequency energy, as well as to improve
the stability and invariability of properties at a
temperature from 4.2 to 50 K the AL-Be alloy is
preferred to be applied. This will allow one to reduce
the consumption of expensive cryogenic liquids, to
decrease the service expenses. Furthermore, the Al-Be
alloy has a low density and high elasticity and possesses
a high technological productivity at the process of
manufacturing the products of a given form: pressing by
rolling, machining [5].
Using the known interpolation formula ([6])
)157,11( 2757,0−+= αRR an
(4)
where α is the characteristic parameter in the anomalous
skin-effect theory (α>1,2), we have found also the
intermediate region between the classic and anomalous
skin affect for Al-Be alloy.
The calculation results have shown that the interme-
diate region between the classical and abnormal skin-
effects for the Al-Be alloy at a frequency of 5.0 GHz
appears at a temperature T∼150 K, the coefficient of
gain η equals to 10 at a frequency of 86.106 GHz. So, to
increase the quality factor of the accelerating structure
of the accelerator by a factor of 10 and more it is
necessary to work at frequencies f≤86 MHz.
REFERENCES
1.F.F. Mende, A.I. Spitsyn. Surface impedance of
superconductors. Kyiv, Naukova Dumka.1985,
p. 20-36 (in Ukrainian).
2.E.L. Hinston. Measurements on the centimeter
waves. Translation from English, edited by
G.L.Remez, Inostrannaya Literatura. 1960, p. 545-
549 (in Russian).
3.V.A. Dvinskikh, Yu.P. Naumenko. Measurement
of the quality factor of microwave resonators // Prib.
Tekhn. Ehksp. 1969, N 1, p. 5-12, (in Russian).
4.E.I. Kulikov. Measurement of the quality factor of
cavity resonators with low damping// Izmerit.
Tekhnika. 1959, N6, p. 55-57 (in Russsian).
5.I.I. Papirov. Beryllium-structural material. M.:
Mashinostroenie. 1971, p. 142-143 (in Russian).
6.R.G. Chambers. The anomalous skin effect //
Pros. Roy. Soc. 1952, v. A215, p. 1123-1125.
96
V.M. Azhazha, K.V. Kovtun, V.A. Kutovoj, N.A. Khizhnyak
MEASUREMENTS
Table 1
Table 2
Table 3
CONCLUSION
REFERENCES
|
| id | nasplib_isofts_kiev_ua-123456789-82265 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T16:44:22Z |
| publishDate | 2000 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Azhazha, V.M. Kovtun, K.V. Kutovoj, V.A. Khizhnyak, N.A. 2015-05-27T11:51:24Z 2015-05-27T11:51:24Z 2000 Investigation of surface resistance OF Al, Be AND Al-Be alloy at low temperatures / V.M. Azhazha, K.V. Kovtun, V.A. Kutovoj, N.A. Khizhnyak // Вопросы атомной науки и техники. — 2000. — № 2. — С. 94-96. — Бібліогр.: 6 назв. — англ. 1562-6016 PACS: 74.72.LW; 71.20.Cf https://nasplib.isofts.kiev.ua/handle/123456789/82265 Our work contains experimental and theoretical studies on the surface resistance of aluminium A999, A99 as a function of annealing temperature, frequency of electromagnetic oscillations, cooling temperature and processing technology. Results of investigation of Al-Be alloy surface resistance in a wide range of low temperatures are presented. The technology of the alloy production and treatment for getting the surface resistance lower then that of initial materials (Al, Be) is described. As we have found, this parameter remains to be a constant in a wide range of low temperatures. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Тheory and technics of particle acceleration Investigation of surface resistance OF Al, Be AND Al-Be alloy at low temperatures Исследование поверхностного сопротивления Al, Be И Al-Be сплава при низких температурах Article published earlier |
| spellingShingle | Investigation of surface resistance OF Al, Be AND Al-Be alloy at low temperatures Azhazha, V.M. Kovtun, K.V. Kutovoj, V.A. Khizhnyak, N.A. Тheory and technics of particle acceleration |
| title | Investigation of surface resistance OF Al, Be AND Al-Be alloy at low temperatures |
| title_alt | Исследование поверхностного сопротивления Al, Be И Al-Be сплава при низких температурах |
| title_full | Investigation of surface resistance OF Al, Be AND Al-Be alloy at low temperatures |
| title_fullStr | Investigation of surface resistance OF Al, Be AND Al-Be alloy at low temperatures |
| title_full_unstemmed | Investigation of surface resistance OF Al, Be AND Al-Be alloy at low temperatures |
| title_short | Investigation of surface resistance OF Al, Be AND Al-Be alloy at low temperatures |
| title_sort | investigation of surface resistance of al, be and al-be alloy at low temperatures |
| topic | Тheory and technics of particle acceleration |
| topic_facet | Тheory and technics of particle acceleration |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/82265 |
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