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Jiting Ouyang - One of the best experts on this subject based on the ideXlab platform.

  • self pulsing in a low current Hollow Cathode Discharge from townsend to glow Discharge
    Physics of Plasmas, 2016
    Co-Authors: Yu Qin, Kan Xie, Yu Zhang, Jiting Ouyang
    Abstract:

    We investigate the self-pulsing phenomenon of a low current cavity Discharge in a cylindrical Hollow Cathode in pure argon. The waveforms of pulsed current and voltage are measured, and the time-averaged and time-resolved images of Hollow Cathode Discharge are recorded by using high-speed intensified charge coupled device camera. The results show that the self-pulsing is a mode transition between low-current stage of Townsend Discharge and high-current stage of glow Discharge. During the self-pulsing, the current rising time relates to the dissipation of space charges, and the decay time relates to the reconstruction of the virtual anode by the accumulation of positive ions. Whether or not space charges can form and keep the virtual anode is responsible for the Discharge mode and hence plays an important role in the self-pulsing phenomenon in low current Hollow Cathode Discharge.

  • self pulsing of Hollow Cathode Discharge in various gases
    Physics of Plasmas, 2014
    Co-Authors: Yu Qin, Kan Xie, X X Jiang, Jiting Ouyang
    Abstract:

    In this paper, we investigate the self-pulsing phenomenon of cavity Discharge in a cylindrical Hollow Cathode in various gases including argon, helium, nitrogen, oxygen, and air. The current-voltage characteristics of the cavity Discharge, the waveforms of the self-pulsing current and voltage as well as the repetition frequency were measured. The results show that the pulsing frequency ranges from a few to tens kilohertz and depends on the averaged current and the pressure in all gases. The pulsing frequency will increase with the averaged current and decrease with the pressure. The rising time of the current pulse is nearly constant in a given gas or mixture. The self-pulsing does not depend on the external ballast but is affected significantly by the external capacitor in parallel with the Discharge cell. The low-current self-pulsing in Hollow Cathode Discharge is the mode transition between Townsend and glow Discharges. It can be described by the charging-discharging process of an equivalent circuit consisting of capacitors and resistors.

  • self pulsing operating mode of Hollow Cathode Discharge in noble gas
    Physics of Plasmas, 2012
    Co-Authors: Jiting Ouyang, Hui Jia
    Abstract:

    The self-pulsing phenomenon of Hollow Cathode Discharge in a semi-cylindrical Hollow Cathode in noble gas is investigated in this paper. The current-voltage (I-V) characteristics and the time evolution of the current and voltage of self-pulsing are measured under different conditions. The results show that the pulse frequency ranges from a few to tens kilohertz depending on the pressure and the averaged current. It increases with the averaged current and decreases as the pressure rising. The external parallel capacitances have no influence on the self-pulsing frequency. It is supposed that the mode transition between pre-Discharge and Hollow Cathode Discharge may contribute to the self-pulse.

M Reiser - One of the best experts on this subject based on the ideXlab platform.

  • high power high brightness electron beam generation in a pulse line driven pseudospark Discharge
    International Conference on Particle Accelerators, 1993
    Co-Authors: W W Destler, Z Segalov, J Rodgers, Kartik Ramaswamy, M Reiser
    Abstract:

    High brightness (/spl sim/3/spl times/10/sup 10/ A/m/sup 2/rad/sup 2/), high power density (/spl sim/10/sup 10/ W/cm/sup 2/) electron beams have been generated by the mating of a Hollow-Cathode Discharge device operating in the pseudospark regime to the output of a high power pulse line accelerator. Very small diameter (/spl sim/1 mm) electron beams with currents in the range 500-1000 A and energies in the range 150-300 keV have been generated with measured effective emittances of about 85 mm-mrad. Such emittances are comparable to those achieved in conventional electron beam sources at current densities several orders of magnitude lower than those observed in these experiments. >

  • high power high brightness electron beam generation in a pulse line driven pseudospark Discharge
    Applied Physics Letters, 1993
    Co-Authors: W W Destler, Z Segalov, J Rodgers, Kartik Ramaswamy, M Reiser
    Abstract:

    High brightness (∼1010 A/m2 rad2), high power density (∼1010 W/cm2) electron beams have been generated by the mating of a Hollow‐Cathode Discharge device operating in the pseudospark regime to the output of a high power pulse line accelerator. Very small diameter (∼1 mm) electron beams with currents in the range 500–1000 A and energies in the range 150–300 keV have been generated with effective emittances estimated to be at or below 170 mm mrad. Such emittances are comparable to those achieved in conventional electron beam sources at current densities several orders of magnitude lower than those observed in these experiments.

M. I. De La Rosa - One of the best experts on this subject based on the ideXlab platform.

  • Application of classical models to high resolution electric field strength falls in a hydrogen glow-Discharge
    Spectrochimica Acta Part B: Atomic Spectroscopy, 2020
    Co-Authors: V. Gonzalez-fernandez, K. Grützmacher, A. Steiger, M. I. De La Rosa
    Abstract:

    This paper presents the application of two classical models to high-resolution electric field measurements carried out in a Hollow Cathode Discharge operated in pure hydrogen plasma. The electric field determination has been done via the Stark shifting and splitting of the 2S level of hydrogen, followed by optogalvanic detection. Two classical models, Rickards' and Wroński's, are applied to these measurements with the objective of obtaining a first estimation on the Discharge dynamics. The chosen models provide an idea of the ions movement, their energy and their mean free path at the Cathode fall region, as well as the electric field strength behaviour depending on the Discharge characteristics.

  • electric field strengths in a Hollow Cathode measured by doppler free two photon optogalvanic spectroscopy via stark splitting of the 2s level of deuterium
    Plasma Sources Science and Technology, 2009
    Co-Authors: M. I. De La Rosa, K. Grützmacher, C. Pérez, L M Fuentes
    Abstract:

    We present, in this work, Doppler-free two-photon optogalvanic spectroscopy as a tool to measure the electric field strength in the Cathode fall region of a Hollow Cathode Discharge via the Stark splitting of the 2S level of atomic deuterium. The strong electric field strength (1 to 4 kV cm−1) present in the Hollow Cathode is determined for various Discharge conditions (currents from 50 to 200 mA and pressures from 400 to 1350 Pa), which allows investigation of the corresponding variations of the Cathode fall and its changes with Discharge operation time.

  • Electric field measurements in a Hollow Cathode Discharge by two-photon polarization spectroscopy of atomic deuterium
    Plasma Sources Science and Technology, 2006
    Co-Authors: M. I. De La Rosa, K. Grützmacher, Ana Bele Gonzalo, C. Pérez, Alexander Steiger
    Abstract:

    The local electric field strength (E-field) is an important parameter to be known in low pressure plasmas such as glow Discharges, RF and microwave Discharges, plasma boundaries in tokamaks etc. In this paper, we demonstrate, for the first time, the potential of two-photon polarization spectroscopy measuring the E-field in the Cathode fall region of a Hollow Cathode Discharge, via Doppler-free spectra of the Stark splitting of the 2S level of atomic deuterium. Electric field strength is determined in the range from 2 to 5 kV cm −1 . Compared with LIF, this method has several advantages: it is not affected by background radiation, it can be applied without limitation at elevated pressure and it allows simultaneous measurement of absolute local atomic ground state densities of hydrogen isotopes.

Liang Wang - One of the best experts on this subject based on the ideXlab platform.

  • PLASMA NITRIDING OF AISI 5140 LOW ALLOY STEEL ASSISTED WITH Hollow Cathode Discharge AT LOW PRESSURE
    Surface Review and Letters, 2017
    Co-Authors: Enbo Wang, Hao Yang, Liang Wang
    Abstract:

    Plasma nitriding of AISI 5140 low alloy steel was carried at pressures ranging from 100Pa–500Pa for 4h with Hollow Cathode Discharge assistance. The treated samples were characterized by optical microscope, microhardness tester, X-ray diffraction and electrochemical workstation. The results show that the compound layer is about 5μm in thickness and the depth of surface hardening layer is about 240μm for the sample nitrided at 100Pa for 4h. The hardness value of nitrided surface is about 830HV0.1, which is about 2.9 times higher than that (290HV0.1) of the substrate. There is no obvious difference in the thickness of compound and diffusion layers, surface microhardness and phase composition of nitrided layers in comparison with that of samples nitrided at pressure 300 and 500Pa used by conventional plasma nitriding. But plasma nitriding with low pressure can effectively reduce the assumption of nitriding gas and amount of exhausted emission.

  • Characteristics of the nitrided layer formed on AISI 304 austenitic stainless steel by high temperature nitriding assisted Hollow Cathode Discharge
    Materials & Design, 2014
    Co-Authors: Shangzhou Zhang, Yongyong He, Lei Zhang, Liang Wang
    Abstract:

    Abstract A series of experiments have been conducted on AISI 304 stainless steel using a Hollow Cathode Discharge assisted plasma nitriding apparatus. Specimens were nitrided at high temperatures (520–560 °C) in order to produce nitrogen expanded austenite phase within a short time. The nitrided specimen was characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, potentiodynamic polarization and microhardness tester. The corrosion properties of nitrided samples were evaluated using anodic polarization tests in 3.5% NaCl solution. The nitrided layer was shown to consist of nitrogen expanded austenite and possibly a small amount of CrN precipitates and iron nitrides. The results indicated that rapid nitriding assisted Hollow Cathode Discharge not only increased the surface hardness but also improved the corrosion resistance of the untreated substrate.

  • plasma nitriding of low alloy steels at floating and cathodic potentials
    Applied Surface Science, 2008
    Co-Authors: Liang Wang, Yang Li, Xuemin Wu
    Abstract:

    The low alloy steels were nitrided in the plasma atmosphere generated by using Hollow Cathode Discharge. For comparison, specimens of 40 Cr steel were in two different potential states. One kind is isolated from Cathode and anode between them the Discharge was created. The other kind is placed on the plate which is connected to the Cathode. The nitriding was carried out at different temperatures. The surface morphology, phase of compound layers and microhardness profiles were analyzed. The optical microscopy observation and X-ray diffraction showed that the compound layers were formed in all experiments. The results of the nitriding treatment are weakly dependent on the potentials applied on the specimens.

W W Destler - One of the best experts on this subject based on the ideXlab platform.

  • high power high brightness electron beam generation in a pulse line driven pseudospark Discharge
    International Conference on Particle Accelerators, 1993
    Co-Authors: W W Destler, Z Segalov, J Rodgers, Kartik Ramaswamy, M Reiser
    Abstract:

    High brightness (/spl sim/3/spl times/10/sup 10/ A/m/sup 2/rad/sup 2/), high power density (/spl sim/10/sup 10/ W/cm/sup 2/) electron beams have been generated by the mating of a Hollow-Cathode Discharge device operating in the pseudospark regime to the output of a high power pulse line accelerator. Very small diameter (/spl sim/1 mm) electron beams with currents in the range 500-1000 A and energies in the range 150-300 keV have been generated with measured effective emittances of about 85 mm-mrad. Such emittances are comparable to those achieved in conventional electron beam sources at current densities several orders of magnitude lower than those observed in these experiments. >

  • high power high brightness electron beam generation in a pulse line driven pseudospark Discharge
    Applied Physics Letters, 1993
    Co-Authors: W W Destler, Z Segalov, J Rodgers, Kartik Ramaswamy, M Reiser
    Abstract:

    High brightness (∼1010 A/m2 rad2), high power density (∼1010 W/cm2) electron beams have been generated by the mating of a Hollow‐Cathode Discharge device operating in the pseudospark regime to the output of a high power pulse line accelerator. Very small diameter (∼1 mm) electron beams with currents in the range 500–1000 A and energies in the range 150–300 keV have been generated with effective emittances estimated to be at or below 170 mm mrad. Such emittances are comparable to those achieved in conventional electron beam sources at current densities several orders of magnitude lower than those observed in these experiments.