Thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration
A process of the thermoacoustic generation inside thin metallic films deposited on the glass substrate was studied. The measurements performed at 8-mm wavelength have showed that an absorption coefficient reaches its maximum in the 2...3-nm aluminum films. The process of sound excitation was studi...
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| Date: | 2004 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2004
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| Cite this: | Thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration / V. Andreev, V. Vdovin, P. Voronov // Вопросы атомной науки и техники. — 2004. — № 2. — С. 200-202. — Бібліогр.: 5 назв. — англ. |
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| author | Andreev, V. Vdovin, V. Voronov, P. |
| author_facet | Andreev, V. Vdovin, V. Voronov, P. |
| citation_txt | Thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration / V. Andreev, V. Vdovin, P. Voronov // Вопросы атомной науки и техники. — 2004. — № 2. — С. 200-202. — Бібліогр.: 5 назв. — англ. |
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| description | A process of the thermoacoustic generation inside thin metallic films deposited on the glass substrate was studied.
The measurements performed at 8-mm wavelength have showed that an absorption coefficient reaches its maximum in
the 2...3-nm aluminum films. The process of sound excitation was studied in a sandwich-type system consisting of
glass – aluminum film – water. It was shown that an efficacy of a themoacoustic excitation for the metallic films of
several tens of angstroms is solely defined by the thermophysical parameters of liquid adjoining to the film surface.
Досліджено процес термоакустичної генерації в тонких металевих плівках, нанесених на кварцову
підкладку. Виміру, проведені на довжині хвилі 8 мм, показали, що коефіцієнт поглинання має максимум при
товщині алюмінієвої плівки 22...25 ангстрем. Поглинання в максимумі склало 34 і 49% при падінні хвилі
відповідно з боку плівки і кварцової підкладки. Явища, що спостерігаються у тонких металевих плівках,
теоретично пояснені з позицій аномального скин-ефекту. Проведено аналіз генерації звуку в шаруватій
системі кварц - алюмінієва плівка – вода. Показано, що при товщинах металевої плівки в кілька десятків
ангстрем ефективність термоакустичної генерації визначається теплофізичними параметрами рідини, що
граничить із плівкою.
Исследован процесс термоакустической генерации в тонких металлических пленках, нанесенных на
кварцевую подложку. Измерения, проведенные на длине волны 8 мм, показали, что коэффициент
поглощения имеет максимум при толщине алюминиевой пленки 22...25 ангстрем. Поглощение в максимуме
составило 34 и 49% при падении волны соответственно со стороны пленки и кварцевой подложки.
Наблюдаемые явления в тонких металлических пленках теоретически объяснены с позиций аномального
скин-эффекта. Проведен анализ генерации звука в слоистой системе кварц - алюминиевая пленка – вода.
Показано, что при толщинах металлической пленки в несколько десятков ангстрем эффективность
термоакустической генерации определяется теплофизическими параметрами граничащей с пленкой
жидкости.
|
| first_indexed | 2025-12-01T00:15:49Z |
| format | Article |
| fulltext |
THIN-FILM TERMOACOUSTIC DETECTOR FOR A REGISTRATION
OF MICROWAVE PULSES OF NANOSECOND DURATION
Valeriy Andreev
Faculty of Physics, Moscow State University, 119899 Moscow, RUSSIA
E-mail: andreev@acs366b.phys.msu.su
Vladimir Vdovin, Pavel Voronov
Institute of Radio Engineering and Electronics, Russian Academy of Sciences
101999 Moscow, RUSSIA
E-mail: vdv@mail.cplire.ru
A process of the thermoacoustic generation inside thin metallic films deposited on the glass substrate was studied.
The measurements performed at 8-mm wavelength have showed that an absorption coefficient reaches its maximum in
the 2...3-nm aluminum films. The process of sound excitation was studied in a sandwich-type system consisting of
glass – aluminum film – water. It was shown that an efficacy of a themoacoustic excitation for the metallic films of
several tens of angstroms is solely defined by the thermophysical parameters of liquid adjoining to the film surface.
PACS: 534.2, 621.385.6
INTRODUCTION
Effect of acoustic transient generation by absorbing
of electromagnetic radiation can be employed for the
development of new type of detectors. Specifically this
technique can be used for the registration of an envelope
of very short (several nanosecond) electromagnetic
pulses [1]. Optoacoustic detectors for visual and
infrared radiation are widely used in science and
industry applications. We propose to use the
thermoacoustic method for the registration of short
pulses of microwave radiation.
Development of an optimal microwave energy
absorber is a principal problem in designing of the
thermoacoustic detector of microwave pulses of
nanosecond duration. For a correct detection of the
temporal profile of the envelope a short microwave pulse
it is necessary to provide the wave absorption in a layer,
which thickness is much less than a length of sound
propagation within pulse duration. For this particular
purpose a process of the thermoacoustic generation inside
thin metallic films deposited on the quartz substrate was
studied.
MOTIVATION OF THE STUDY
In our previous works [1,2] it was shown that the
short microwave pulse can be detected with
thermoacoustic receiver provided the thickness of the
layer of the pulse absorption is much smaller than the
pulse duration: . The conductive
materials could be employed as absorbers of microwave
energy. In a conductive material with a conductivity σ
the wave with frequency f is absorbed at the depth of a
skin layer:
1
0 )( −>> cR ατ
21
0 )( −= σμμπfd , where μ is the magnetic
conductivity, μ0 is the magnetic constant (μ0 = 4π·10-7
H/m). It can be shown that perfectly conductive metals
Al and Cu could be employed for the thermoacoustic
conversion of microwave energy to the acoustic one.
But the efficiency of energy conversion is very small
due to strong reflection of microwave waves from the
metallic surface. Typical value for the reflection
coefficient is 99.5%, therefore only 0.5% of the incident
energy can be converted to the acoustic pulse. The aim
of our study was to find the absorbers where the
efficiency of the microwave energy conversion to
acoustic pulse was as much as possible. For this purpose
the optical coefficients of thin metallic films were
studied.
OPTICAL PROPERTIES OF THE THIN
ALUMINUM FILMS
Measurements of the optical properties of aluminum
films deposited on the glass substrate were performed.
Microwaves with 8 mm wavelength were employed.
Radiation was directed on the film surface from air or
through the glass substrate (Fig.1). Results of the
measurements are shown in Fig.2. Reflection of Al-film
was monotonically induced with growth of the film
thickness and its value became equaled to unity for
thicknesses larger than 10 nm. Correspondently the
coefficient of transmittance was reduced and it
practically vanished at the film thicknesses 6...8 nm.
The values of transmittance coefficient were
completely identical for cases of microwave incidence
from air (Fig.2,a) and from glass (Fig.2,b). The
absorption coefficient reached maximum value in the
thicknesses range 2...3 nm, the measured maximum
value of absorption when the wave fell from the glass
substrate (�m=0.49) was higher than the wave fell from
air side (�m=0.34). Theoretical analysis of the wave
behavior in a three-layer structure was performed on the
basis of Maxwell equations and empirical dependence
of a conductivity of the thin film on its thickness. For
the three-layer structure we obtained the following
solution:
( )
( )
2
2
13
13
2
2
⎟
⎠
⎞
⎜
⎝
⎛ ++
⎟
⎠
⎞
⎜
⎝
⎛ +−
=
b
dnn
b
dnn
R ,
( )
2
13
31
2
4
⎟
⎠
⎞
⎜
⎝
⎛ ++
=
b
dnn
nnT ,
___________________________________________________________
PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 2.
Series: Nuclear Physics Investigations (43), p.200-202. 200
( )
2
13
1
2
8
⎟
⎠
⎞
⎜
⎝
⎛ ++
=
b
dnn
n
b
d
A , (1)
where d is the film thickness, πσ2cb = , σ is the metal
conductivity, n1 and n3 are the indexes coefficients of
201
Fig.1. Aluminum film with d thickness sputtered on the
quartz glass substrate (n3=1.5)
media from direction of radiation incidence and after
metallic film correspondently (see Fig.1). Here the
conductivity is a function the film thickness which is a
result of electron reflections from the film boundaries:
0000 )),/(ln1)(2/()( lddlldd <+= σσ (2)
where σо is the specific conductivity of metal, lo is the
mean length of a free propagation of an electron in thick
metal. The coefficient h is also a function of
conductivity: h(d)=c/2πσ(d).
0 3 6 9 12
0.0
0.2
0.4
0.6
0.8
1.0
15
A
T
R
C
oe
ffi
ci
en
ts
R
,T
,A
Film thickness, nm a
0 3 6 9 12
0.0
0.2
0.4
0.6
0.8
1.0
Fig.2. Dependence of the coefficients of reflection (R),
transmittance (T) and absorption (A) on the aluminum
film thickness. Microwave radiation falls on the film
surface from air directly (a), or being transmitted
through a glass substrate (b). Theoretical curves
calculated using formulas (1,2) are shown by the solid
lines, experimental results are presented with symbols
(● - R, ○ - T, * - A )
Theoretical dependencies of the optical coefficients
R,T,A calculated according to formulas (1,2) are
presented in Fig.2 by solid lines. We used the following
constants values σо=3.54·107 Сm/m, lo = 15 nm,
hо= πσ2c о=0.135 nm.
n3
d
Microwave
radiation
λ=8mm
n1
ACOUSTIC PULSE GENERATION
A schematic diagram for a thermoacoustic pulse
excitation by short microwave burst is shown in Fig.3.
The aluminum film sputtered on the surface of 4-mm
glass substrate was used as absorber of microwave
radiation of 8-mm wavelength. Glass plate reflected
30% of incident energy and another 70% was penetrated
into glass and propagated to the aluminum film surface.
Here almost 50% of passing energy was reflected and
remaining energy produced the thermoacoustic pulse.
Energy of microwave burst is absorbed mainly
inside metallic film deposited on the glass substrate
transparent for microwaves and in water layer contacted
with the film from the opposite side.
Fig.3. Principal scheme of excitation of thermoacoustic
pulses in a thin metallic layer sputtered on the glass
substrate
15
A
T
R
C
oe
ffi
ci
en
ts
R
,T
,A
Film thickness, nm b
Due to extremely small thickness of the film and high
conductivity of metal heat produced inside the film is
practically instantly diffuses into the glass substrate and
into liquid located another side of the film (see Fig.3).
Therefore sound is produced inside regions where heat
can penetrate during the pulse duration. Liquid provides
the higher values of Grunizen parameter and the
efficiency of sound inside liquid layer is dominated.
Acoustic pulse excited in absorbing aluminum layer
propagated through water layer of 3-mm thickness. Wide-
band ultrasonic transducer made of PVDF film of 30µm
thickness was used for detection of acoustic pulse. The
pressure sensitivity of the receiving transducer was of
about 20 µV/Pa in the frequency range from1 to 80 MHz.
Microwave
pulse
radiation
Liquid
layer
Heat
diffusion
volume
Glass
substrate
Ultrasonic
transducer
Aluminum
film
Modeling of the thermoacoustic pulse excitation in the
sandwich-like structure was performed.
A set of equations that includes equation of motion
and thermodiffusivity equation were solved
numerically. Results of numerical simulations are
presented in Fig.4. We employed a method of transfer
function for the calculation. The transfer function of the
system containing glass layer, thin aluminum film of
varied thickness and water layer was calculated.
Transfer function is uniform up to 200 MHz for small
(d<5 nm) thicknesses. Thickness growth results in
reduction of transfer function in high frequency region.
The waveform of the thermoacoustic pulse is presented
in Fig.4.
00 10 20 30 40 50 6
0
1000
2000
P
re
ss
ur
e,
P
a
time, ns
Fig.4. Temporal profiles of acoustic transient excited in
aluminum film. Microwave pulse with Gaussian
waveform was specified at the entrance of the system
Gaussian profile of the incident microwave burst
with 10 ns duration was specified for numerical
simulations. Profile of the thermoacoustic pulse
replicates the corresponding waveform of the
microwave burst for small thicknesses and then it
became broader. We can estimate that for 2 nm
aluminum film with maximum absorption the peak
pressure value can be up to 2000 Pa. Maximum signal
voltage will be about 40 mV. This value 1.5 times
exceeds the noise level produced by capacitor discharge.
It makes us optimistic to detect the thermoacoustic pulse
experimentally in spite of extremely low incident
microwave energy (1 mJ).
This work was supported by RFBR grant # 01-02-17344
REFERENCES
1. V.G.Andreev, A.A.Karabutov, V.A.Vdovin Basic
principles of thermo-acoustic energy and temporal
profile detection of microwave pulses // Problems of
atomic science and technique. 2001, v.39, №5, p.24-
26.
2. V.G.Andreev, A.A.Karabutov, V.A.Vdovin Device
for registration of a microwave pulse envelop and its
energy. Patent of Russian Federation №2194284,
2002.
3. V.E.Gusev, A.A.Karabutov. Laser optoacoustics.
Moscow: Nauka, 1991.
4. G.E.H.Reuter, E.H.Sondheimer // Proc. Roy. Soc. A.
1948, v.195, № 1042, p.336-364.
5. A.E.Kaplan // Radiotechnique and Electronics.
1964, v.9, №10, p.1781-178.
ТОНКОПЛЕНОЧНЫЙ ТЕРМОАКУСТИЧЕСКИЙ ДЕТЕКТОР ДЛЯ РЕГИСТРАЦИИ ИМПУЛЬСОВ
СВЧ ИЗЛУЧЕНИЯ НАНОСЕКУНДНОЙ ДЛИТЕЛЬНОСТИ
В.Г. Андреев, В.А. Вдовин, П.С. Воронов
Исследован процесс термоакустической генерации в тонких металлических пленках, нанесенных на
кварцевую подложку. Измерения, проведенные на длине волны 8 мм, показали, что коэффициент
поглощения имеет максимум при толщине алюминиевой пленки 22...25 ангстрем. Поглощение в максимуме
составило 34 и 49% при падении волны соответственно со стороны пленки и кварцевой подложки.
Наблюдаемые явления в тонких металлических пленках теоретически объяснены с позиций аномального
скин-эффекта. Проведен анализ генерации звука в слоистой системе кварц - алюминиевая пленка – вода.
Показано, что при толщинах металлической пленки в несколько десятков ангстрем эффективность
термоакустической генерации определяется теплофизическими параметрами граничащей с пленкой
жидкости.
ТОНКОПЛІВКОВИЙ ТЕРМОАКУСТИЧНИЙ ДЕТЕКТОР ДЛЯ РЕЄСТРАЦІЇ ІМПУЛЬСІВ СВЧ
ВИПРОМІНЮВАННЯ НАНОСЕКУНДНОЙ ТРИВАЛОСТІ
В.Г. Андрєєв, В.А. Удовин, П.С. Воронов
Досліджено процес термоакустичної генерації в тонких металевих плівках, нанесених на кварцову
підкладку. Виміру, проведені на довжині хвилі 8 мм, показали, що коефіцієнт поглинання має максимум при
товщині алюмінієвої плівки 22...25 ангстрем. Поглинання в максимумі склало 34 і 49% при падінні хвилі
відповідно з боку плівки і кварцової підкладки. Явища, що спостерігаються у тонких металевих плівках,
теоретично пояснені з позицій аномального скин-ефекту. Проведено аналіз генерації звуку в шаруватій
системі кварц - алюмінієва плівка – вода. Показано, що при товщинах металевої плівки в кілька десятків
ангстрем ефективність термоакустичної генерації визначається теплофізичними параметрами рідини, що
граничить із плівкою.
202
Valeriy Andreev
Faculty of Physics, Moscow State University, 119899 Moscow, RUSSIA
E-mail: andreev@acs366b.phys.msu.su
Institute of Radio Engineering and Electronics, Russian Academy of Sciences
101999 Moscow, RUSSIA
INTRODUCTION
MOTIVATION OF THE STUDY
REFERENCES
|
| id | nasplib_isofts_kiev_ua-123456789-79397 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-01T00:15:49Z |
| publishDate | 2004 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Andreev, V. Vdovin, V. Voronov, P. 2015-03-31T19:34:46Z 2015-03-31T19:34:46Z 2004 Thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration / V. Andreev, V. Vdovin, P. Voronov // Вопросы атомной науки и техники. — 2004. — № 2. — С. 200-202. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS: 534.2, 621.385.6 https://nasplib.isofts.kiev.ua/handle/123456789/79397 A process of the thermoacoustic generation inside thin metallic films deposited on the glass substrate was studied. The measurements performed at 8-mm wavelength have showed that an absorption coefficient reaches its maximum in the 2...3-nm aluminum films. The process of sound excitation was studied in a sandwich-type system consisting of glass – aluminum film – water. It was shown that an efficacy of a themoacoustic excitation for the metallic films of several tens of angstroms is solely defined by the thermophysical parameters of liquid adjoining to the film surface. Досліджено процес термоакустичної генерації в тонких металевих плівках, нанесених на кварцову підкладку. Виміру, проведені на довжині хвилі 8 мм, показали, що коефіцієнт поглинання має максимум при товщині алюмінієвої плівки 22...25 ангстрем. Поглинання в максимумі склало 34 і 49% при падінні хвилі відповідно з боку плівки і кварцової підкладки. Явища, що спостерігаються у тонких металевих плівках, теоретично пояснені з позицій аномального скин-ефекту. Проведено аналіз генерації звуку в шаруватій системі кварц - алюмінієва плівка – вода. Показано, що при товщинах металевої плівки в кілька десятків ангстрем ефективність термоакустичної генерації визначається теплофізичними параметрами рідини, що граничить із плівкою. Исследован процесс термоакустической генерации в тонких металлических пленках, нанесенных на кварцевую подложку. Измерения, проведенные на длине волны 8 мм, показали, что коэффициент поглощения имеет максимум при толщине алюминиевой пленки 22...25 ангстрем. Поглощение в максимуме составило 34 и 49% при падении волны соответственно со стороны пленки и кварцевой подложки. Наблюдаемые явления в тонких металлических пленках теоретически объяснены с позиций аномального скин-эффекта. Проведен анализ генерации звука в слоистой системе кварц - алюминиевая пленка – вода. Показано, что при толщинах металлической пленки в несколько десятков ангстрем эффективность термоакустической генерации определяется теплофизическими параметрами граничащей с пленкой жидкости. This work was supported by RFBR grant # 01-02-17344. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Применение ускоренных пучков Thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration Тонкоплівковий термоакустичний детектор для реєстрації імпульсів СВЧ випромінювання наносекундной тривалості Тонкопленочный термоакустический детектор для регистрации импульсов СВЧ излучения наносекундной длительности Article published earlier |
| spellingShingle | Thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration Andreev, V. Vdovin, V. Voronov, P. Применение ускоренных пучков |
| title | Thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration |
| title_alt | Тонкоплівковий термоакустичний детектор для реєстрації імпульсів СВЧ випромінювання наносекундной тривалості Тонкопленочный термоакустический детектор для регистрации импульсов СВЧ излучения наносекундной длительности |
| title_full | Thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration |
| title_fullStr | Thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration |
| title_full_unstemmed | Thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration |
| title_short | Thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration |
| title_sort | thin-film termoacoustic detector for a registration of microwave pulses of nanosecond duration |
| topic | Применение ускоренных пучков |
| topic_facet | Применение ускоренных пучков |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79397 |
| work_keys_str_mv | AT andreevv thinfilmtermoacousticdetectorforaregistrationofmicrowavepulsesofnanosecondduration AT vdovinv thinfilmtermoacousticdetectorforaregistrationofmicrowavepulsesofnanosecondduration AT voronovp thinfilmtermoacousticdetectorforaregistrationofmicrowavepulsesofnanosecondduration AT andreevv tonkoplívkoviitermoakustičniidetektordlâreêstracííímpulʹsívsvčvipromínûvannânanosekundnoitrivalostí AT vdovinv tonkoplívkoviitermoakustičniidetektordlâreêstracííímpulʹsívsvčvipromínûvannânanosekundnoitrivalostí AT voronovp tonkoplívkoviitermoakustičniidetektordlâreêstracííímpulʹsívsvčvipromínûvannânanosekundnoitrivalostí AT andreevv tonkoplenočnyitermoakustičeskiidetektordlâregistraciiimpulʹsovsvčizlučeniânanosekundnoidlitelʹnosti AT vdovinv tonkoplenočnyitermoakustičeskiidetektordlâregistraciiimpulʹsovsvčizlučeniânanosekundnoidlitelʹnosti AT voronovp tonkoplenočnyitermoakustičeskiidetektordlâregistraciiimpulʹsovsvčizlučeniânanosekundnoidlitelʹnosti |