J. Plasma Fusion Res. SERIES, Vol.7 (2006) 135-137

Remote Monitoring of Silica Absorption Doseby Means of Ionoluminescence
KONONENKO Sergiy I., KALANTARYAN Oganes V., MURATOV Volodimir I. and NAMBA Chusei1
Kharkov National University, Kharkov, Ukraine
1 National Institute for Fusion Science, Toki 509-5292, Japan（Received: 5 October 2004 / Accepted: 3 October 2005）

Abstract
The silica ionluminescence spectra induced by fast proton bombardment were studied. Luminescent radiation angular characteristics were measured. The relation between light intensity and both absorption doseand observation angle was determined. The novel methods for control of proton dose (up to 3 × 10 21 particles
per cm3 ) in quartz were proposed.
Keywords:
ionluminescence, spectrum, silica, absorption dose, light ion, angular characteristic
1．Introduction
The use of silica as insulators and windows in thermonuclear facilities is widespread. The silica grids are
one of the main parts of secondary emission radioisotope source of current (SERICS). The properties of silica grid have an influence on operation of this device.
Nondestructive monitoring of this property changes is
one of the most important tasks of radiation physics.
In thermonuclear reactor silica optic elements areused both for optical diagnostics and for microwave radiation input into chamber as lenses and light guides,
which constitute optical channel. Physical, chemical and mechanical properties of these materials arechanged during particle flux irradiation from a thermonuclear plasma. It comes out from formation, annealing and establishment of a dynamic equilibrium between diﬀerent types of defects induced by radiation.
Luminescent light of the silica under irradiation is either alternative to the process of defect formation, oraccompanying ones. In this connection, a luminescence
spectrum includes important information about instantaneous dynamic equilibrium of the defect distribution
in the solid and is unique channel of radiation process
remote monitoring.
The ionoluminescence spectra of quartz are changed
essentially during proton irradiation [1]. Based of thesedates the novel method was proposed for monitoring
proton dose in SiO2 . The changing of ionoluminescence angular characteristics under ion irradiation inmegaelectronvolt region of energy was studied also [2].
The angular and spectral characteristics of silica luminescence during light ion bombardment were studied

for improvement of our method.
2．Results
The experiments were carried out using hydrogenions with energy from 210 to 420 keV. The wavelength
range of ionoluminescence study was from 400 to 700
nm. Incident and observation angles were varied from20◦ to 70◦ . Luminescence spectra were studied for absorption dose up to 3 × 1021 particles per cm3 .
The typical luminescence spectrum of nonirradiatedsilica under ion bombardment is shown in Fig.1 (a).
The first band with maximum near 456 nm was themost intensive. This band was associated with intrinsic
silica defects namely E −centers. Other oxygen deficiency centers could take part in generation of this light.
The second band with maximum near 650 nm was situated on the long wave side of the first band. The nonbridging oxygen centers were associated with this band.
Increasing proton dose changed the luminescence
spectra. The intensity of the long wave side of the firstband increased (see Fig. 1 (b)). The intensity of second band decreased as long as this band become almost
indistinguishable at the background of the first band.
For comparison of experimental spectra obtained under diﬀerent conditions we used normalization of spectra intensities I (λ) to spectral intensity maximum offirst band (for wave length 456 nm) I (456):In (λ) = I(λ)/I (456),
where In (λ) is normalized spectral intensity for wave
C 2006 by The Japan Society of Plasma

Science and Nuclear Fusion Research

Corresponding author’s e-mail: kononenko@htuni.kharkov.ua.

135

Remote Monitoring of Silica Absorption Dose by Means of Ionoluminescence(a)Fig. 2 The ionoluminescence normalized spectra of nonirradiated SiO2 under proton bombardment, beamenergy 420 keV, incidence angle 30◦ : 1 - observation angle 0◦ , 2 - observation angle 30◦ , 3 - observation angle 60◦ .

(b)Fig. 1 The ionoluminescence spectra of SiO2 under proton bombardment, beam energy 420 keV, incidence angle 30◦ , observation angle 30◦ :(a). nonirradiated sample;(b). 1 - nonirradiated sample, 2 - absorption dose
5×1020 particles per cm3, 3 - absorption dose
3×1021 particles per cm3.

Fig. 3 Angular dependences of the normalized ionoluminescence spectra1 light (λ = 456 nm) of SiO2 under proton bombardment, beam energy 420 keV,incidence angle 30 ( : 1 - nonirradiated sample,
2 - absorption dose 5×1020 particles per cm3, 3 absorption dose 3×1021 particles per cm3.

length λ. This normalization permits to study changing of spectral shape for diﬀerent observation angles,incident angles, absorption dose, species and energy ofions.
The nonirradiated silica normalized spectra at diﬀerent observation angles are shown in Fig.2. The spectra
have the main diﬀerence in the region, corresponding tosecond band wavelength location (see Fig. 2). The normalized intensity of second band increased with growthof observation angle. Absorption dose increase changed
the ionoluminescence spectrum shape [1]. But when thedose exceeded ∼ 5 × 1020 particles per cm3 the shape of
normalized spectra did not depend on observation angle. The similar results were obtained for all species
and energy of ions.
The angular characteristics of luminescence in maximum of the first band (456 nm) were studied. We used

the technique in detail described in [2]. The spectral
intensity I (β) was normalized to its value corresponding to observation angle equal 0◦ (indicatrix maximum
I (0◦ )), i.e.
In (β) = I(β)/I(0◦ ),where In (β) is normalized intensity. The dependences
measured must follow Lambert law:
I = I0 cos(β),
where I is intensity corresponding observation angle β,
I0 is indicatrix maximum corresponding to observation
angle 0◦ . It was reasonably that normalized indicatrix
were divided by cos (β).

136Remote Monitoring of Silica Absorption Dose by Means of Ionoluminescence

The luminescence spectral normalized indicatrix taking into account Lambert law is shown on the Fig.3.
The parameter for these curves is absorption dose. In
the case when the dose exceeds ∼ 5 × 1020 particles per
cm3 the normalized indicatrix shape does not change.
The similar results were obtained for all species and energy of ions.

to increase of the collecting solid angle for luminescence light. It will increase sensibility of the proposaltechnique.
4．Conclusion
The new technique for absorption dose monitoring
was proposed. This technique based on changes of luminescence spectra and their angular characteristics under ion bombardment.
Methods based on measurements of luminescence
spectrum shape and angular characteristics can be used
for absorption dose not exceed 5 × 1020 particles per
cm3 . These methods can be used as independent techniques, which supplement each other.
For doses more than 5 × 1020 particles per cm3 using
only changes in the luminescence spectrum shape it ispossible to carry out the absorption dose monitoring.
Sensibility of the method can be increased by means ofcollecting solid angle increasing.

3．Discussion
As is shown, the shape of the luminescence spectra
depends on both absorption dose of the sample and observation angle. It takes place for doses that not exceed
5 × 1020 particles per cm3 . These eﬀects can be used
for remote measurements of sample absorption dose.
Dose dependences can be explained by dynamic of intrinsic defect and projectile distributions in bulk of thesolid. The first band presence is determined above allby self-trapped exciton decay (see for example [3]).
Distance between the formation place and the decay
place of the exciton can be quite large; its value canexceed interatomic distances many times [3]. The second band is a result of intrinsic defect non-bridging oxygen center (see for example [3]). The dynamic of bothsuch intrinsic defects and implant hydrogen determinechanges in luminescence spectra with absorption dosein silica samples. Such eﬀects can take place in othersubstances where excitons can be excited (for example,alkali-halogen crystals).
To monitor absorption dose in mentioned above
range both spectrum shape and angular characteristicchanging can be used. Methods based on measurementsof luminescence spectrum shape and angular characteristics can be used as independent techniques, which
supplement each other.
For doses more than 5 × 1020 particles per cm3 theangular characteristics of luminescence are invariable,
but spectrum shape changing. In this case, using onlychanging in the luminescence spectrum shape it is possible to carry out the absorption dose monitoring. Moreover, the invariability of angular characteristics permits

Acknowledgements
This work is carried out in the framework of thescience collaboration of Kharkov National University
named by Karazin, Ukraine and National Institute for
Fusion Science, Toki Japan. The work was supported
by Science and Technology Center in Ukraine projectNo 1862. The authors would like to appreciate the great
contribution of prof. A. Shishkin to the evolution ofthis problem and useful discussions. We thank to V.
Zhurenko for significant help in the work.

[1]
[2]

[3]137

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