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Neo Y.,University of Shizuoka | Masuzawa T.,University of Shizuoka | Aoki T.,University of Shizuoka | Mimura H.,University of Shizuoka | And 3 more authors.
IVNC 2015 - Technical Digest: 28th International Vacuum Nanoelectronics Conference | Year: 2015

Graphite nanoneedles (GRANN) and graphite emitter inflamed at high temperature (GFEIHT) are known to exhibit unique field emission properties: the brightness of these emitters are as high as that of CNT, while these emitters can achieve high emission current of 2 mA. In this study, graphite-based field emitters were fabricated and their surface structures were investigated in order to explain their unique field emission properties. © 2015 IEEE.


Iwai Y.,Onizuka Glass Corporation | Iwai Y.,University of Shizuoka | Jyouzuka A.,Onizuka Glass Corporation | Jyouzuka A.,University of Shizuoka | And 10 more authors.
Proceedings of the International Display Workshops | Year: 2012

The characteristics of processed graphite field emitters named graphite nanospines (GNS) and graphite field emitter inflamed at high temperature (GFEIHT) have been investigated. Those emitters can emit a relatively larger current of 2 mA. We also report X-ray tubes using those emitters and its applications.


Iwai Y.,Onizuka Glass Corporation | Iwai Y.,University of Shizuoka | Koike T.,Onizuka Glass Corporation | Jyouzuka A.,Onizuka Glass Corporation | And 4 more authors.
Technical Digest - 2014 27th International Vacuum Nanoelectronics Conference, IVNC 2014 | Year: 2014

We have fabricated two type of graphite field emission cathodes: graphite nanospines (GNS) and graphite field emitters inflamed at high temperatures (GFEIHT) and applied for X-ray tubes using these cathodes. The morphologies and structures of the two cathodes were quite different. However, these emitters have excellent field emission characteristics. Raman spectroscopy indicated that GFEIHT consisted of many graphene tips without crystalline defects. © 2014 IEEE.


Jyouzuka A.,Onizuka Glass Co. | Jyouzuka A.,University of Shizuoka | Nakamura T.,Onizuka Glass Co. | Onizuka Y.,Onizuka Glass Co. | And 3 more authors.
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics | Year: 2010

The emission characteristics of graphite nanospines (GNSs) encapsulated in an x-ray tube with a system for controlling electric field crowding (SCEFC) are investigated. GNSs encapsulated in an x-ray tube can be driven at an anode current (IA) of more than 1 mA. Further, IA can be controlled using the SCEFC. During the operation of the x-ray tube with GNSs and the SCEFC at the anode voltage of 12.5 kV and IA of 640 μA for 100 h, there was no degradation in IA. The noise current superimposed on IA was observed to be ±34.5 μA. It was reduced to ±1.62 μA by using the SCEFC. The authors also demonstrated radiography and x-ray fluorescence measurement as applications of x-ray tubes with GNSs and the SCEFC. © 2010 American Vacuum Society.


Iwai Y.,Onizuka Glass Company Ltd | Iwai Y.,Incubation Alliance Incorporated | Muramatsu K.,Incubation Alliance Incorporated | Tsuboi S.,Onizuka Glass Company Ltd | And 4 more authors.
Applied Physics Express | Year: 2013

We have successfully fabricated a filament-less X-ray tube using a graphene flower cloth (GFC) field emission cathode. The GFC has numerous nanoprotrusions formed by self-standing graphene structures. The field emission current and the field enhancement factor β were 500 μA and 5600, respectively. The stability of voltage defined as a variance coefficient (σ/mean) of voltage was calculated to be 0.04% while maintaining the X-ray tube current of 300 μA. We applied our X-ray tube with the GFC field emitter to the X-ray fluorescence (XRF) analysis of stainless steel. © 2013 The Japan Society of Applied Physics.


Iwai Y.,Onizuka Glass Co. | Iwai Y.,University of Shizuoka | Koike T.,Onizuka Glass Co. | Hayama Y.,Onizuka Glass Co. | And 5 more authors.
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics | Year: 2013

The authors developed a class of novel graphite-based field emitters, known as graphite field emitters inflamed at high temperature (GFEIHTs), which includes numerous edges and juts. The GFEIHT field emission characteristics are investigated in a vacuum tube (10-7 Pa), and an anode current exceeding 2 mA is obtained. The authors also fabricated tipped-off x-ray tubes using GFEIHTs. No degradation in the anode current is observed under the operating conditions of 16.6 kV anode voltage and 160 μA anode current. The current dispersion, defined as the standard deviation (σ)mean over 24 h, is 2.8. The authors successfully demonstrated radiography and x-ray fluorescence spectrometry using an x-ray tube with GFEIHT. © 2013 American Vacuum Society.


Jyouzuka A.,Onizuka Glass Co. | Jyouzuka A.,University of Shizuoka | Koike T.,Onizuka Glass Co. | Nakamura T.,Onizuka Glass Co. | And 2 more authors.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

We report a low-power-loss and high voltage X-ray tubes with a graphite nanospines (GNS) cold cathode. The cathode is encapsulated in a glass tube having a Beryllium window with a Tantalum film to generate X-rays. The internal tube pressure was below 10-7 Pa and a tube current exceeding 1 mA at a tube voltage of 22.9 kV was observed in the fabricated X-ray tube. The tube current dispersion, defined as standard deviation/mean (σ/mean), was relatively small at 2.4%. An X-ray radiation dose rate exceeding 5 Sv/h was obtained from the X-ray tube and the radiation dose rate dispersion was also small (σ/mean=0.3%). As an application of the X-ray tube, we demonstrated radiography for the rapid inspection of organic products. © 2011 Elsevier B.V. All rights reserved.


Koike T.,Onizuka Glass Co. | Jyouzuka A.,Onizuka Glass Co. | Jyouzuka A.,University of Shizuoka | Nakamura T.,Onizuka Glass Co. | And 3 more authors.
Proceedings - IVNC 2011: 2011 24th International Vacuum Nanoelectronics Conference | Year: 2011

We report a new carbon material with nanostructures, known as inflamed graphite at high temperature (IGHT). IGHT is fabricated by inflaming material in a mixture of hydrogen and oxygen gas at a temperature exceeding 2000 °C. Fabricated IGHTs are encapsulated in a glass chamber in order to estimate the field emission current. The chamber pressure is as high as 10-7 Pa. A field emission current exceeding 350 μA is obtained from IGHT. An IGHT emits a stable current with a low current dispersion below the standard deviation/mean (σ/mean) of 2%.σ/mean reveals that the IGHT withstands ion bombardment.

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