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Li D.,Lanzhou Institution of Physics | Zhang H.,Lanzhou Institution of Physics | Feng Y.,Lanzhou Institution of Physics | Chen Y.,Lanzhou Institution of Physics | And 3 more authors.
2013 26th International Vacuum Nanoelectronics Conference, IVNC 2013 | Year: 2013

Study of the ionization gauge with carbon nanotube cathode for carbon nanotube (CNT) field emission cathode, a high gate electrode voltage, as high as several hundred volts, is required to generate high emission field current. However, high gate potentials could affect the electric field distribution in the ionization space significantly, and the electron energies endowed by gate potential are relatively high for the gas ionization. Both of them have negative impacts on the ionizatio Simulation n probability. In this work, the structure of the ionization gauge with CNT cathode was optimized from the simulation study. The results show that electron trajectory in the ionization space vary with the change of the voltage ratio between the anode and the gate (V grid/Vgate). For extractor gauge, the longest effective electron trajectory could be achieved when the ratio of Vgrid/V gate reaches 1.6. The sensitivity decreases with increasing the anode potential, which is due to the drop of the ionization probability caused by the high anode potential. Accordingly, a new cathode structure is proposed with adding a suppressor electrode between the gate and the anode. The suppressor electrode is help to decrease the electron energy, leading the increase of the sensitivity. This design provides a new approach to extend the measurement lower limit for CNT field emission based ionization gauge. © 2013 IEEE.

Zhang J.,Wenzhou University | Li D.,Wenzhou University | Li D.,Lanzhou Institution of Physics | Zhao Y.,Wenzhou University | And 3 more authors.
Nanoscale Research Letters | Year: 2016

The field emission properties and the vacuum measurement application are investigated from the multi-walled carbon nanotubes (MWNTs) grown directly on catalytic stainless steel substrates. The MWNT emitters present excellent emission properties after the acid treatment of the substrate. The MWNT gauge is able to work down to the extreme-high vacuum (XHV) range with linear measurement performance in wide range from 10−11 to 10−6 Torr. A modulating grid is attempted with improved gauge sensitivity. The extension of the lower pressure limit is attributed largely to low outgassing effect due to direct growth of MWNTs and justified design of the electron source. © 2016, Zhang et al.

Zhang J.,Wenzhou University | Zhao Y.,Wenzhou University | Cheng Y.,Lanzhou Institution of Physics | Li D.,Wenzhou University | And 3 more authors.
IVNC 2015 - Technical Digest: 28th International Vacuum Nanoelectronics Conference | Year: 2015

The ultra-high vacuum measurement properties are investigated on the Leybold extract gauge based on carbon nanotube (CNT) field emission. The CNT field emitters are grown directly on catalytic substrates with strong nanotube adhesion, excellent emission properties, and low outgassing effect. The CNT gauge responds linearly to nitrogen pressure in the range from 10-6 to 10-11 Torr with sensitivities of about 3 torr-1, under the anode current of 46μA and the anode votagle of 430V. The measurement of pressure down to 10-12 torr is expected under higher cathode current and the addition of a shielding electrode to constrain the electron energy in order to improve the gas ionization efficiency and minimize the EDS & x-ray effects. © 2015 IEEE.

Li D.,Wenzhou University | Li D.,Lanzhou Institution of Physics | Myneni G.,Jefferson Lab | Dong C.,Wenzhou University | Dong C.,Lanzhou Institution of Physics
Proceedings of 2015 IEEE International Vacuum Electronics Conference, IVEC 2015 | Year: 2015

The field emission behaviors of multi-walled carbon nanotubes (CNTs) electron source are investigated. The CNT emitters were grown directly on the Ni alloy substrate by the chemical vaopor deposition. Anode current 41 μA under 310 V gate voltage with the electron transmission rate of about 70-75%, only about 10% lower than the gate transparency. The electric field generated from the anode could penetrate through the gate grid to enhances the field emission by 30-50 %. There could be a serious pressure rise in the operation due to mainly the molecule desorption from the metal electrodes (gate and anode) by the electron bombardment. © 2015 IEEE.

Xie F.,Wenzhou University | Dong C.,Wenzhou University | Dong C.,Lanzhou Institution of Physics | Qian W.,Wenzhou University | And 4 more authors.
International Journal of Hydrogen Energy | Year: 2015

Abstract The electrochemical properties of nickel-metal hydride (Ni-MH) batteries with directly grown multi-walled carbon nanotubes (MWNTs) have been investigated. MWNTs interwove through active material powders to benefit the battery in three aspects: enhancing the electrode mechanical strength by clutching the active material to the substrate, improving the electrochemical activity from the increase of the reaction sites, and reducing the charge transfer resistance as conducting bridges. The battery with MWNTs exhibited excellent electrochemical properties with the maximum discharge specific capacity of 360.9 mAh/g, 18% higher than the electrode without MWNTs, and EIS analysis showed that the charge transfer resistances dropped 37.5%. Meanwhile, the charge-discharge cycle stability was improved dramatically with the additions of both MWNTs and PTFE binder, declining 10.8% only after 220 cycles. This MWNT/Ni foam structure is also very promising for other electrochemical applications. © 2015 Hydrogen Energy Publications, LLC.

Feng Y.,Lanzhou Institution of Physics | Zhang R.,Lanzhou Institution of Physics | Sheng X.,Lanzhou Institution of Physics | Dong M.,Lanzhou Institution of Physics | Zhao L.,Lanzhou Institution of Physics
Applied Mechanics and Materials | Year: 2013

On laboratory conditions, background leakage caused by temperaturechange wasone of the most important factorsfor affectingcalibration of pressure leak,consequently, the constant temperature water bath of the calibration apparatus has been used to reduce background leakage by means of keeping the apparatus temperature constant. The method of active and passiveness were combined to keep constant temperature. through the research on experimentation, it was found thatbackground leakage was decreased to the grade of 1.36×10-9Pa m3/s when constant temperature been used,and meanwhile the lower limitingof pressure leak was extended to 2.667×10-8Pa m3/s. © (2013) Trans Tech Publications, Switzerland.

Zhang R.,Lanzhou Institution of Physics | Feng Y.,Lanzhou Institution of Physics | Zhao L.,Lanzhou Institution of Physics | Sheng X.,Lanzhou Institution of Physics | Dong M.,Lanzhou Institution of Physics
Applied Mechanics and Materials | Year: 2013

This Research was based on domestic and international pressure leak calibration technology, respectively, constant volume method and constant pressure(two model: saw-tooth variation constant pressure measurement mode and digital PID measurement mode) were both used on identical pressure leak calibration, 10-6 Pa•m3/s level, then, measurement uncertainty analysis of each method and the calibration results were compared. © (2013) Trans Tech Publications, Switzerland.

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