Laser Thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications
Laser Thomson scattering was applied to plasma diagnostics almost as soon as laser was invented in 1960. The most important contribution of the technique to plasma physics and controlled fusion came from the confirmation of good confinement of plasmas in the T-3 tokamak in 1968, by a collaboration...
Збережено в:
| Дата: | 2006 |
|---|---|
| Автор: | |
| Формат: | Стаття |
| Мова: | English |
| Опубліковано: |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2006
|
| Назва видання: | Вопросы атомной науки и техники |
| Теми: | |
| Онлайн доступ: | http://dspace.nbuv.gov.ua/handle/123456789/82352 |
| 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: | Laser Thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications / Katsunori Muraoka // Вопросы атомной науки и техники. — 2006. — № 6. — С. 236-240. — Бібліогр.: 18 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
irk-123456789-82352 |
|---|---|
| record_format |
dspace |
| spelling |
irk-123456789-823522015-05-29T03:02:05Z Laser Thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications Muraoka, Katsunori Plasma diagnostics Laser Thomson scattering was applied to plasma diagnostics almost as soon as laser was invented in 1960. The most important contribution of the technique to plasma physics and controlled fusion came from the confirmation of good confinement of plasmas in the T-3 tokamak in 1968, by a collaboration of Russian and British physicists. Since then, extensive developments of the technique have been made to meet various measurement requirements, not only in hightemperature plasmas but in plasmas for industrial applications. In this article, these developments are briefly reviewed, followed by the work of the author and its implications for understanding various plasma phenomena. 2006 Article Laser Thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications / Katsunori Muraoka // Вопросы атомной науки и техники. — 2006. — № 6. — С. 236-240. — Бібліогр.: 18 назв. — англ. 1562-6016 PACS: 52.70.-m,52.70.Kz http://dspace.nbuv.gov.ua/handle/123456789/82352 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| topic |
Plasma diagnostics Plasma diagnostics |
| spellingShingle |
Plasma diagnostics Plasma diagnostics Muraoka, Katsunori Laser Thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications Вопросы атомной науки и техники |
| description |
Laser Thomson scattering was applied to plasma diagnostics almost as soon as laser was invented in 1960. The most
important contribution of the technique to plasma physics and controlled fusion came from the confirmation of good
confinement of plasmas in the T-3 tokamak in 1968, by a collaboration of Russian and British physicists. Since then,
extensive developments of the technique have been made to meet various measurement requirements, not only in hightemperature
plasmas but in plasmas for industrial applications. In this article, these developments are briefly reviewed,
followed by the work of the author and its implications for understanding various plasma phenomena. |
| format |
Article |
| author |
Muraoka, Katsunori |
| author_facet |
Muraoka, Katsunori |
| author_sort |
Muraoka, Katsunori |
| title |
Laser Thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications |
| title_short |
Laser Thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications |
| title_full |
Laser Thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications |
| title_fullStr |
Laser Thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications |
| title_full_unstemmed |
Laser Thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications |
| title_sort |
laser thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2006 |
| topic_facet |
Plasma diagnostics |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/82352 |
| citation_txt |
Laser Thomson scattering diagnostics - developments and applications to high-temperature plasmas and plasmas for industrial applications / Katsunori Muraoka // Вопросы атомной науки и техники. — 2006. — № 6. — С. 236-240. — Бібліогр.: 18 назв. — англ. |
| series |
Вопросы атомной науки и техники |
| work_keys_str_mv |
AT muraokakatsunori laserthomsonscatteringdiagnosticsdevelopmentsandapplicationstohightemperatureplasmasandplasmasforindustrialapplications |
| first_indexed |
2025-07-06T08:51:28Z |
| last_indexed |
2025-07-06T08:51:28Z |
| _version_ |
1836886931821035520 |
| fulltext |
236 Problems of Atomic Science and Technology. 2006, 6. Series: Plasma Physics (12), p. 236-240
LASER THOMSON SCATTERING DIAGNOSTICS
-DEVELOPMENTS AND APPLICATIONS TO HIGH-TEMPERATURE
PLASMAS AND PLASMAS FOR INDUSTRIAL APPLICATIONS
Katsunori Muraoka
School of Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan
Laser Thomson scattering was applied to plasma diagnostics almost as soon as laser was invented in 1960. The most
important contribution of the technique to plasma physics and controlled fusion came from the confirmation of good
confinement of plasmas in the T-3 tokamak in 1968, by a collaboration of Russian and British physicists. Since then,
extensive developments of the technique have been made to meet various measurement requirements, not only in high-
temperature plasmas but in plasmas for industrial applications. In this article, these developments are briefly reviewed,
followed by the work of the author and its implications for understanding various plasma phenomena.
PACS: 52.70.-m,52.70.Kz
1. INTRODUCTION
lthough the principle of laser Thomson scattering (LTS,
here the author refers only to the incoherent region of
laser Thomson scattering from plasmas [1]) has been
known and used for diagnosing electron properties in
plasmas for many years, ingenious developments for
various applications have been necessary to meet
requirements at each plasma and surrounding conditions.
In this article, the author describes how these
developments have been made worldwide and mentions
his own experiences of measuring electron density and
temperature, or more generally electron energy distri-
bution function (eedf), in plasmas, for the last 35 years.
2. BRIEF SURVEY OF LTS
The principle and general experimental arrange-ment
of LTS have been described in detail in various references,
e.g. [1,2]. The author divides developments of LTS to
three stages, as shown in Fig. 1.
The first stage is the development of LTS started by
using a single-pulse ruby laser for high-temperature
plasma studies in the middle of 1960’s, and culminated in
the confirmation of performance claimed for the T-3
tokamak in 1968 [3]. Refinements, such as TVTS
(television Thomson scattering) [4] and LIDAR (light
detection and ranging) Thomson scattering, [5] to meet
the requirements of a very high spatial resolution and an
optical access limitation, respectively, followed.
The second stage started in the late 1980s. Here, data
accumulation has been of essence for plasmas having
electron densities ne below 1018 m-3. This is because the
scattered photon numbers, Np, from a plasma having
electron density of ne are typically expressed as
Np = 10-17 ne. Plasmas having ne below 1018 m-3 were
started to be used in industrial applications around 1980,
and understanding of their electron properties was highly
required then.
The third stage concerns the application of LTS to
micro-discharge plasmas formed as close as 100 m to a
material surface and was prompted by the need to
improve the efficiency of plasma display panels (PDPs) in
particular. The suppression of stray light from the surface
was of utmost importance, and a triple-grating
spectrometer played an essential part here.
Each stage is still under developments to meet even
higher measurement requirements and more and more
stringent measuring environments. In this respect,
specific examples from the work of the authors are
described in detail.
3. THE FIRST STAGE LTS
The importance of LTS on the T-3 tokamak [3] can
hardly be overstated in plasma physics in two senses; namely
it had cleared the pessimism surrounding fusion researches in
late ’60 and has recently been culminated in the ITER project,
while the other aspect was that plasma researchers in general
recognized the usefulness and importance of laser
diagnostics methods in general and many people started to
doubt ne and Te unless obtained using LTS!
LTS has progressed significantly since the T-3
experiment. There have been three directions in the
developments. The first is the TVTS (television Thomson
scattering) system developed at PPPL in USA [4]. This
system, first installed on PLT and then on TFTR
Fig. 1. Three stages of LTS for measurements of electron properties in plasmas
237
tokamaks, collects scattered signals from many points
along the laser beam using a large collection lens and
focused onto a multi-channel optical fiber system, which
are then sent to a set of spectrometers. In this way,
information of ne and Te is two-dimensionally displayed
against spatial points along the laser beam (thus the term
TV). Signals from 74 points along the laser beam could
be detected, with a spatial resolution of 10 mm. The
second direction is to use a high-repetition YAG laser,
developed at Garching in Germany [6]. In this way,
temporal developments of ne and Te were obtained at a
frequency of more than 100 Hz.
The third direction is the LIDAR (light detection and
ranging) LTS system, first conceived at Stuttgart University
in Germany and jointly developed with JET [5]. This system
uses the same window for the laser input and scattered light
detection, and the spatial resolution is obtained with the time-
of-flight principle using a very short laser pulse and a fast
detector. The author had a collaborative work on the LIDAR
LTS system to use a streak camera for obtaining a very high
spatial resolution [7].
The author has also applied the single-pulse LTS to
various DC and pulse discharges [1] in which ne >1018 m-3
[see below in Section 4 for this inequality of ne]. One
example of such measurements is that applied to a
discharge pumped excimer laser [8]. Because the duration
of the discharge is about 50 ns, one wants to get a
temporal resolution of the order of 1 ns. Thus, a laser
light from the second harmonic generator (SHG) of a
mode-locked YAG laser was used, and the scattered light
was dispersed using a double-monochoromator to have a
high rejection of stray light and detected using a set of
photomultipliers.
Figure 2 is an example of measured spectra, showing
the intensity of scattered signals measured at different
wavelengths, from a gas mixture of
Kr/F/Ne=30 Torr/1.5 Torr/3 atm (a standard gas mix for a
KrF laser). The measured spectral points could be fitted
with a straight line [on this graph with the abscissa of
(∆λ)2, the wavelength displacement from the laser
wavelength squared, against the ordinate of log(signal)] ,
and this indicates that f(ve) is a Maxwellian distribution. A
numerical simulation of the discharge for these conditions
predicted that f(ve) would be non-Maxwellian distribution.
The measurements, however, indicate that f(ve) be in fact
Maxwellian, and so the model used for the simulation was
modified to take into account electron-electron collisions,
which had been neglected previously. The results of the
newer simulation are also shown in Fig. 2 by the thick
solid line, and agree satisfactorily with the measurements.
By using this system, temporal developments of ne
and Te of an excimer laser discharges were measured for
the first time, as shown in Fig. 3. It may have been
impossible to get this information by other means.
4. THE SECOND STAGE LTS
The Thomson scattered photon number, Ns, is described as
∆ΩησTe
L
s lS'nSEN /
= , (1)
where EL is the laser energy, S is the laser beam spot size,
h is the photon energy, ne is the electron density in m-3,
S’l is the scattering volume, T is the Thomson cross
section per unit solid angle, is the solid angle of
observation and is the transmission coefficient.
Fig. 2. Thomson scattering spectra for a gas mixture of
Kr/F2/Ne=30 Torr/1.5 Torr/3 atm in a plasma for a
discharge-pumped excimer laser
Fig. 3. Temporal evolution of electron temperature Te and
electron density ne for a gas mixture of
Kr/F2/Ne=30 Torr/1.5 Torr/3 atm in a plasma
for a discharge-pumped excimer laser
By inserting appropriate numbers for a typical experimental
situation (EL = 1 J, = 4×10-19 J for = 500 nm, S = S’ ,
l = 0.01 m, T = 9×10-30 m2sr-1, =10-3 sr and η = 0.1),
one obtains
Ns = 2×10-17ne (photons). (2)
There are areas of improvements in the above numbers,
such as increases of the laser energy and in the solid angle
of observation. However, the quantum efficiency of a
photo-detector, such as a photomultiplier, and spectral
resolution requirements counter-balance these
improvements, and one concludes that ne >1018 m-3 is the
minimum detectable electron density for a single- pulse
LTS. This is an electron density region typical of high-
temperature plasmas and some classes of plasmas for
industrial applications, as described in Section 3.
A data accumulation process technique, taking advantage
of DC or repetitive operations of some discharges, has been
suggested for reducing the limiting electron densities [9]. Such
studies have been performed for ECR (electron cyclotron
resonance), ICP (induction-coupled plasma) and NLD
(neutral-line discharge), and, combined with photon counting,
have recently achieved a minimum detectable electron density
of 5×1015 m-3. Some examples are shown in the following,
238
which show particular strength of LTS, the data of which are
difficult to obtain by other means.
4.1. DEPARTURE FROM MAXWELLIAN EEDF
One of the most important aspects of LTS is its
capability for making a direct measurement of the eedf.
This was exploited to study electron behavior in ICP
discharge [10]. To characterize electron behavior in the
argon ICP discharge, LTS spectra were measured under
various experimental conditions. Figure 4 shows such
measurements, measured for various argon gas pressures
at the plasma center for an input rf power of 500 W.
Because the abscissa and the ordinate are the same as for
Fig. 2, the straight line indicates a Gaussian distribution.
In this expression, we used the value directly measurable
in the spectrometer, but it is to be noted that ( )2= 10nm2
corresponds to 4.3 eV. Spectra for high pressures do have
Gaussian shapes, indicating Maxwellian eedf. At lower
pressures, however, the LTS spectra are non-Gaussian,
which indicates that the eedfs are non-Maxwellian.
Fig. 4. Thomson scattering spectra from Ar plasmas at
various pressures. The measurements were made on an
ICP at the plasma center with an input rf power of 500 W
Spatial and temporal distributions were measured for
different input powers and pressures, and the temporal
changes after switching off the input power were also
observed. The results of these measurements are
summarized as follows:
(a) The eedfs were clearly non-Maxwellian for some
discharge conditions.
(b) These eedfs did not change during the rf cycle. The
characteristic times over which the eedfs were observed
to change were on the order of microseconds rather
than nanoseconds.
(c) The shapes of the eedfs did not vary noticeably with
position in the plasma.
Physical interpretations of the observations were
discussed in [11].
Recently, this capacity to measure eedfs directly was
applied to reactive plasmas. Non-Maxwellian eedfs,
similar to those shown in Fig. 4, observed when even
small concentrations of CF4 are present in argon
discharges, are attributed to the effect of electron-
molecule vibrational excitation collisions [12].
4.2. Bi-MAXWELLIAN EEDF
A common feature of many probe studies in low-pressure
capacitively coupled rf glow discharges is the observation of a
non-Maxwellian eedfs for some discharge conditions. A
measured bi-Maxwellian eedf was explained by insufficient
energy exchange between the high-temperature component,
arising from stochastic electron heating in the rf sheaths, and
the low-temperature component formed by being trapped in
the central potential well.
In order to confirm this observation, LTS was applied
to a capacitively coupled rf glow discharge. Figure 5
shows an LTS spectrum measured at the center of the
discharge at an argon pressure of 100 mTorr and an rf
power of 40 W [13]. The data were obtained by
accumulating scattered signals for 12000 laser shots. It
can be seen from the figure that the spectrum is fitted by
two straight lines with different slopes, indicating that the
eedf for this condition is bi-Maxwellian, with two
components of electrons characterized by different
temperatures and densities.
Fig. 5. Thomson scattering spectrum measured on a
CCP at the center of the discharge at an Ar pressure of
100 mTorr and an rf power of 40 W with an instrumental
half width of a spectrometer of 0.37 nm. The data were
accumulated for 12,000 shots
The properties of the two components were determined
from the spectrum to be Te = (4.6 ± 1.6) eV and
ne = (1.2 ± 0.22) × 1016 m-3 for the high-temperature
component, and Te= (0.2 ± 0.02) eV and ne = (1.76 ± 0.10)×
×1017 m-3 for the low-temperature component. It is to e noted
that the monochromator had a reciprocal dispersion of
0.45 nm/mm, and the slit width of 1 mm yielded the
measured instrumental width of 0.42 nm FWHM. This value
was taken into account to calculate the above temperatures,
e.g. Te = (0.25±0.02) eV was derived from the Thomson
width of 1.26 nm FWHM, which was the deconvolved value
of the measured spectral FWHM of 1.30 nm and the above
instrumental width.
This and other results provided independent confirmation
of the existence of non-Maxwellian eedfs in these discharges
for low-pressure conditions. In addition, by adjusting the slit
widths of the monochromator used to detect the scattered
spectra, we were able to clearly resolve the low energy part
of the eedf, which is difficult using probes.
It is to be noted that it was in this low-pressure capacitively
coupled rf discharges that the minimum detectable electron
density of ne =5×1015 m-3 was obtained [14].
4.3. TEMPERATURE ANISOTROPY
Another strength of LTS is its capability of detecting a
temperature anisotropy by simply changing the scattering
wave-vector relative to the plasma geometry. An experiment
239
was carried out to measure velocity distribution function on an
ECR system perpendicular and parallel to the magnetic field.
he measured Te and ne are plotted for different operating
pressures for the ECR plasma in Fig. 6 [15]. These
results indicate that ne increases almost linearly, and Te
decreases first but reaches a constant value, with
increasing gas pressure in this pressure range. Also, a
temperature anisotropy, detected in the low pressure range
for the first time, can be seen in Fig. 6(b).
Fig. 6. Electron density (a) and temperature (b)
measured as a function of the Ar gas pressure. In (b) the
open and closed circles represents temperatures parallel
and perpendicular to the magnetic field, respectively
5. THE THIRD STAGE LTS
During the last few years, LTS measurements have
been performed on plasmas formed less than 100 µm
away from a material surface [16], employing a triple-
grating spectrometer having a rejection of above 10-8 at
1 nm away from the laser wavelength.
The technique was applied to a micro-discharge
simulating a PDP (Plasma Display Panel) discharge. By
using appropriate laser powers and working gas mixtures,
spatial distributions of Te and ne in the range of -
1.0<x<1.5 mm (x is the coordinate along the electrode
surface) were measured at times up to 1.0 µs from
application of voltage, where we chose x=0 to be at the
middle of the electrode gap and x>0 for the temporal
cathode side. The results are shown in Fig. 7.
Recently, the spatial resolution of measurements has
been improved to 60 µm, so that a striation phenomenon,
a very prominent feature of this discharge, can now be
spatially resolved [17]. Figure 8 shows one of the results.
The most remarkable feature of the measurement is that
the modulation in Te is completely out of phase with the
modulation in ne.
Fig.7. Spatial distributions of electron density ne (a) and
electron temperature Te (b) at a position of Z=0.1 mm in a
discharge simulating a plasma display panel
Fig.8. Spatial distributions of electron density ne (a)
and electron temperature Te (b) of a striated plasma
simulating a plasma display panel
Fig. 9. Spatial distributions of electron density (above)
and electron energy (below) of a striated plasma
simulating a plasma display panel obtained using a
Monte-Carlo numerical simulation
(a)
(b)
X [m m ]
0 .0
1 .0
2 .0
3 .0
4 .0
0 .0
1 .0
2 .0
3 .0
4 .0 t = 0.22
t = 0.26
t = 0.30
el
ec
tr
on
te
m
pe
ra
tu
re
[
eV
]
el
ec
tr
on
d
en
st
iy
[
~ 10
19
m
-3
]
4 .0
0 .0
0 0 .5 1.0 1 .5- 0 .5- 1 .0
Cathode sideAnode side gap 0.1mm
[µ s]
(a)
(b)
X [m m ]
0 .0
1 .0
2 .0
3 .0
4 .0
0 .0
1 .0
2 .0
3 .0
4 .0 t = 0.22
t = 0.26
t = 0.30
el
ec
tr
on
te
m
pe
ra
tu
re
[
eV
]
el
ec
tr
on
d
en
st
iy
[
~ 10
19
m
-3
]
4 .0
0 .0
0 0 .5 1.0 1 .5- 0 .5- 1 .0
Cathode sideAnode side gap 0.1mm
[µ s]
1x1024
8x1023
6x1023
4x1023
2x1023
0
10
8
6
4
2
0
0 0.2
X (mm)
density
average energy
El
ec
tro
n
de
ns
ity
(a
rb
. u
ni
t)
El
ec
tro
n
av
er
ag
e
en
er
gy
(e
V
)
0.4 0.6 0.8 1
a
b
240
Monte-Carlo simulation has been performed for this
discharge condition [18]. Figure 9 illustrates one of such
simulations, showing the modulations having the same
characteristic as for Fig. 8. This is explained by the
sudden deceleration of electrons upon impinging from a
cathode fall where the electric field is very high into a
positive column where the electric field is weak.
6. SUMMARY
In summarizing the foregoing results and discussion,
one concludes that the first and the second stages LTS are
more or less established and routine measurements can be
made for any plasma, if conditions are right, such as
having sufficient value of ne and observation
environments. Specific environments for LTS
measurements may require additional developments, such
as LIDAR LTS for ITER divertor plasmas. On the other
hand, the third stage LTS still needs active developments,
aiming at the spatial resolution of 1 µm, an almost
diffraction limit for visible lasers. This may open up a
possibility of applying LTS into various interesting
plasma phenomena, such as studying sheath plasmas very
close to electrode surfaces.
ACKNOWLEDGEMENTS
The author wishes to thank those who have contributed
various phases of the work described in this article. This
work has been supported by a grant from the High-Tech
Research Center Establishment Project from the Ministry of
Education, Culture, Sports, Science and Technology of Japan.
REFERENCES
1.K. Muraoka and M. Maeda. Laser-Aided Diagnostics of
Plasmas and Gases. U. K.: IOP Publishing, 2000.
2.K. Muraoka, K. Uchino and M. D. Bowden// Plasma
Phys. Control. Fusion. 1998, 40, p. 1221.
3.N.J. Peacock, D.C. Robinson, M.J. Forrest, P. Wilcock
and V.V. Sannikov// Nature. 1968, v.224, p. 448.
4.D. Johnson, D. Dimock, B. Grek, D. Long, D. McNiell,
R. Palladino, R. Robinson and E. Tolnas// Rev. Sci.
Instrum. 1985, v.56, p.1015.
5.H. Salzmann, K Hirsch, P. Nielsen, C. Gowers, Gadd,
M. Gadeburg, H. Murmann and A. Schrodter// Nuclear
Fusion. 1987, v.27, p.1925.
6.H.Roehr, K.-H.Steuer, G.Schramm, K. Hirsch,
H. Salzmann// Nuclear Fusion. 1982, v.22, p.1099.
7.C. Gowers, H. Fajemirokun, T. Hender, T. Kajiwara,
P. Nielsen and B. Schunke// JET-IR(92)09. 1992.
8.K. Uchino, Y. Kubo, H. Dozono, H. Yamakoshi,
K. Muraoka, M. Maeda, A. Takahashi and M Kato//
Appl. Phys. 1995, B61, p.165.
9.T. Sakoda, S. Momii, K. Uchino, K.Muraoka,
M. D. Bowden, M. Maeda, Y. Manabe, M. Kitagawa
and T. Kimura// Jpn. J. Appl. Phys. 1991, v.30, L1425.
10. T. Hori, M. D. Bowden, K. Uchino and K. Muraoka//
Appl. Phys.Lett. 1996, v.69, p.3683.
11. T. Hori, M. D. Bowden, K. Uchino and K. Muraoka//
J. Appl. Phys. 1998, v.83, p.1909.
12. M. D. Bowden, R. Tabata, P. Suanpoot, K. Uchino,
K. Muraoka, M. Noguchi// J. Appl. Phys. 2001, v.90,
p. 2158.
13. M. Mansour, M. D. Bowden, K. Uchino and
K. Muraoka// Appl. Phys. Lett. 2001, v.78, p.3187.
14. M. Mansour, M. Koyama, M. D. Bowden, K. Uchino,
K. Muraoka// Jpn. J. Appl. Phys. 2001, v.40, p.1465.
15. M. D. Bowden, T. Okamoto, F. Kimura, H. Muta,
K. Uchino, K. Muraoka, T. Sakoda, M. Maeda,
Y. Manabe, M. Kitagawa and T. Kimura// J. Appl.
Phys. 1993, v.73, p. 2732.
16. Y. Noguchi, Y. Matsuoka, M. D. Bowden, K. Uchino,
K. Muraoka// Jpn. J. Appl. Phys. 2001, v.40, p.326.
17. S. Hassaballa, K. Tomita, Y. K. Kim, K. Uchino,
H. Hatanaka, Y. M. Kim, C. H. Park and K. Muraoka//
Jpn. J. Appl. Phys. 2005, v.44, L442.
18. K. Muraoka, M. Azumi, K. Suzuki, Y. Yamagata and
M. Yagi// J. Phys.D: Appl. Phys. 2006, v.39, p.2135.
:
1960 .
, 1968 .
-3.
, ,
. ,
.
:
1960 .
, 1968 .
-3.
, ,
. ,
.
|