2014 Annual Meeting of The Institute of Electrostatics JapanHiroshima International University
September 7-8, 2014

8pD-1
September 8th (Mon.), <15:00-16:30>
Room 3Development of low-particle-emission corona discharge
ionizer by electrode heating. Part.3 ，○Tomokatsu SATO*，Masanori SUZUKI*，Akira MIZUNO***Technical R&D Center, Techno Ryowa Ltd，**Dept. Environmental and Life
Sciences, Toyohashi University of Technology

Abstract:
Corona discharge type ionizers are widely utilized in clean rooms, suchas those for LCD manufacturing processes. However, these ionizers are also
known to generate particles due to deposition of particles to tip of the electrodes
and then these particles are eventually released into air of clean room. In orderto resolve this problem, we devised a method for inhibiting the deposition ofparticles to tip of the electrodes by heating the electrodes to utilize thethermophoretic force to repel fine particles towards low temperature region. In
the previous paper, we conducted an experiment on heating an ionizer electrodeto approximately 90℃, the amount of deposition of particle on the electrodedecreased in comparison with a case of the non-heating. In addition, as apractical heating method of ionizer electrode, we devised a self-heating-type
electrode using the Joule heating of the resistor. As a result of this experiment,
we found that it was possible to heat the electrode to the desired temperature. In
this paper, we report the results of investigation on heating characteristics ofself-heating-type electrode.

2014 Annual Meeting of The Institute of Electrostatics Japan
Hiroshima International University
September 7-8, 2014

8pD-2
September 8th (Mon.), <15:00-16:30>
Room 3Generation process of induction surge from the chargedbody.
○Kenta WATANABE and Hirofumi SHIMOKAWA

Abstract:
In this study, we used the van-der-Graaf generator type that can easily
generate high voltage. A copper wire is being put from the generator at somedistance. Other end of the wire is being put near metal plate grounded. The
spark discharge was generated between wire and metal plate, when thegenerator operated. The purpose of this study is to clarify the surge
phenomenon that occurs when an object having a high charge potential

2014 Annual Meeting of The Institute of Electrostatics Japan
Hiroshima International UniversitySeptember 7-8, 2014

8pD-3
September 8th (Mon.), <15:00-16:30>
Room 3

Influence of nitrogen concentration of atmosphere onignitability of powders
Kwangseok CHOI*，Koujirou NISHIMURA***JNIOSH、**TIISAbstract:
As useful method to prevent dust explosions, inerting using nitrogen(N2), which is an incombustible gas, has been used in industries. This paper is areport of the relationship between the minimum ignition energy (MIE) of powders
due to an electrostatic sparks and the minimum oxygen concentration (MOC) forcombustion. In this paper, we have changed the N2 amount in the air in order tocontrol the oxygen concentration. The Hartman vertical-tube apparatus wasused in this study. The control range of the dust concentrations of the MIE
apparatus used in this study is from 0.5 kg/m3 to 1.8 kg/m3. The maximum sparkenergy achieved in this study was 1000 mJ. Six sample powders were used in
the experiment. As a result, the inerting of N2 has an effect on the ignitability ofsample powders as expected. The MIE of all powders used in this studyincreased due to the increase in the amount of N2 in the air. We finally suggestthat 84 % (or above) of N2 for inerting affects the prevention of dust explosionsof polymer powders due to electrostatic sparks.

2014 Annual Meeting of The Institute of Electrostatics Japan
Hiroshima International University
September 7-8, 2014

8pD-4
September 8th (Mon.), <15:00-16:30>
Room 3Development of Electrostatic Ground Monitoring Device○Tomofumi Mogami, Fumiaki Hashimoto, Tomoju Hirota, Teruo Suzuki, Fumio
Yamada, Nobuo Nomura
Kasuga Denki INC

Abstract:
Of the industrial accidents of fires and/or explosions due to electrostatic
discharges, spark discharges are most frequent ignition source. To solve andprevent spark discharges, all the groundings of the conductors need to bechecked. We have developed an electrostatic ground monitoring device. The
electrostatic ground monitoring device mainly has two ground wire connections,pin A which is connected to the ground and pin B which is connected to the LED.
The electrostatic ground monitoring device can be detected in less than theresistance value (below 100 kΩ) defined in static safety guidelines. This
electrostatic ground monitoring device is expected to be very useful and reliablein preventing problems originating from spark discharges.

2014 Annual Meeting of The Institute of Electrostatics JapanHiroshima International University
September 7-8, 2014

8pD-5
September 8th (Mon.), <15:00-16:30>
Room 3

Breakdown Characteristics across Micrometer-scale
Surface Gaps under Negative Impulse Voltage
Hiroyuki IWABUCH
Department of Electrical Engineering and Information Systems

Abstract:
With the miniaturization of MEMS devices, the insulation width and theseparation between electrodes in such devices have been accordingly reduced.
Consequently, electrical breakdown phenomenon across micrometer-scale gap
is of great practical interest for insulation designing of miniaturized devices. This
paper reports breakdown phenomenon under negative impulse voltage
application across micrometer-scale surface gaps fabricated on SO wafers.
When applying the negative impulse voltage, the breakdown voltage wasconstant and independent of gap width and electrode material. The result
indicates that the breakdown voltage was strongly affected by the electric
intensity on the cathode: the F-N current by the electric field on the cathode can
induce the breakdown.