By Topic

Plasma Science, IEEE Transactions on

Issue 8 • Date Aug. 2013

Filter Results

Displaying Results 1 - 25 of 40
  • Table of contents

    Page(s): C1 - 2229
    Save to Project icon | Request Permissions | PDF file iconPDF (169 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Plasma Science publication information

    Page(s): C2
    Save to Project icon | Request Permissions | PDF file iconPDF (135 KB)  
    Freely Available from IEEE
  • Influence of Electric Field on Stabilization of Flame From Poor Methane–Oxygen Mixture

    Page(s): 2230 - 2236
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1412 KB) |  | HTML iconHTML  

    This paper deals with the influence of the dc electric field on the stabilization of the flame created from a poor (lean) mixture of methane and oxygen. In our experiments, the electric field is created between two electrodes in a combustion chamber in which one of the electrodes is a part of a burner. The dc voltage from a high voltage source is applied to both electrodes. A mixture of methane and oxygen with the purity of 99.95% of both gases is used for the combustion process. The burner combustion power is set at 0.5 kW. The observations of the electric field effects on the stabilization of the flame are carried out by increasing the oxygen flow up to the flame extinction. The result of the measurement is the observed electric field influence on the stabilization of the flame that is created from a poor mixture of methane and oxygen. In the experiment, we observe the dependence between flame stabilization and supplied electrical energy. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Semi-Empirical Calculation Method of the Positive First Corona Space Charge Under Different Impulse Rising Rates in Long Air Gaps

    Page(s): 2237 - 2245
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1734 KB) |  | HTML iconHTML  

    In this paper, the variation of the development of positive first corona space charge in long air gaps is investigated. A 1-m rod-plane air gap under different rising rates $dU/dt$ of impulse voltages is reported. The current signals and still photographs are recorded during the first corona development. The relationship between the first corona charge $Q_{{rm i}}$ and the inception voltage $U_{{rm i}}$ is presented. The physical mechanism of the influence of the first corona is provided. With the experiments and the single branch propagation model, a semi-empirical calcultion method for positive first corona charge under impulse in long air gaps is obtained through the calculation of the number of branches $N_{{rm b}}$. Using this method, the variations between $Q_{{rm i}}$ and $U_{{rm i}}$ for different $dU/dt$ and electric field distributions are calculated and compared with the reported experimental results. Reasonable agreement between the calculated and experimental results is obtained. It shows that this calculation method is suitable for predicting the positive first corona charge $Q_{{rm i}}$ and the discharge current at a given $dU/dt$ and $U_{{rm i}}$. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Accurate Calculation of High Harmonics Generated by Interactions Between Very Intense Laser Fields and Electron Plasmas

    Page(s): 2246 - 2250
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (334 KB) |  | HTML iconHTML  

    In a recent paper, we proved that the analytical expression of the intensity of the relativistic Thomson scattered field for a system composed of an electron interacting with a plane electromagnetic field can be written as a periodic function of only one variable, that is, the phase of the incident field. This property is proved without using any approximation, except for neglecting the radiative corrections; in the most general case, in which the field is elliptically polarized, the initial phase of the incident field and the initial velocity of the electron are taken into consideration, and the direction in which the radiation is scattered is arbitrary. This property led to an exact method for calculating the angular and spectral distributions of the scattered field. We apply this method to the case of the interaction of very intense laser beams with electron plasmas resulted during the ionization of gas. We calculate the shape of the spectrum of the scattered radiations and show that the number of the harmonics increases as the value of the relativistic parameter increases. The high harmonics spectrum has a maximum shifting to the shorter wavelengths. The method accurately predicts the angular distribution of the scattered radiations. All these properties are in good agreement with the experimental data from the literature. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Sensitiveness of Decentered Parameter for Relativistic Self-Focusing of Hermite-cosh-Gaussian Laser Beam in Plasma

    Page(s): 2251 - 2256
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (956 KB) |  | HTML iconHTML  

    Sensitiveness of the decentered parameter for relativistic self-focusing of Hermite-cosh-Gaussian beam in the plasma is investigated theoretically using Wentzel-Kramers-Brillouin and paraxial ray approximation for mode indices 0, 1, and 2. The plot between the beam width parameter and the normalized propagation distance for different values of the decentered parameter and intensity has been reported and results obtained indicate the dependency of the self-focusing of the laser beam on the decentered parameter. The selection of the decentered parameter is more sensitive to self-focusing. For the mode indices ${rm m}={0}$ and 1, self-focusing becomes stronger and for ${rm m}={2}$, self-focusing becomes weaker as the diffraction term becomes more dominant. Our emphasis is on the selection of the decentered parameter at which stronger self-focusing of laser beam is observed which might be very useful in the applications, such as the generation of inertial fusion energy driven by lasers, laser driven accelerators, and so on. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Temporal Growth Study in Trapezoidally Corrugated Slow-Wave Structure for Backward-Wave Oscillator

    Page(s): 2257 - 2263
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (597 KB) |  | HTML iconHTML  

    The temporal growth rate (TGR) in a trapezoidally corrugated slow-wave structure for a backward-wave oscillator is theoretically studied. An intense relativistic annular electron is used as the energy source for the device. The annular electron beam is assumed to be infinitesimally thin in the radial extent and guided by an infinitely strong magnetic field. The trapezoidal profile of the structure is approximated by a sinusoidal function using Fourier approximation, and the dispersion relation of the system is derived using the Rayleigh–Fourier method. To study the TGR of the electromagnetic wave inside the system, the dispersion equation is solved for different values of the beam parameters. The dimensions of sinusoidally corrugated comparable trapezoidal structure are determined by comparing their dispersion characteristics. For the ${rm TM}_{01}$ mode, TGR of instability that gives a qualitative measure of the microwave generation is calculated. The peak TGR of the proposed structure is found to be on average 1.5% higher than that of the sinusoidally corrugated slow-wave structure for the same set of beam parameters. Apart from its improved growth rate, the proposed structure has an added advantage of easy fabrication. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design and Simulation of Lossy Interaction Structure for Ka-Band Gyro-TWT

    Page(s): 2264 - 2268
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (547 KB) |  | HTML iconHTML  

    In this paper, beam-wave interaction analysis in a Ka-band periodically ceramic loaded gyrotron traveling-wave tube (gyro-TWT) amplifier is investigated using particle-in-cell (PIC) simulation. The simulations predict that the interaction structure can produce more than 80-kW output power, 50-dB saturated gain, and 3-dB bandwidth is 2.56 GHz for 65 kV and 5-A electron beam with velocity ratio $(alpha)$ of 1.2. The dispersion and interaction impedance characteristics of the ceramic-loaded gyro-TWT amplifier are also determined using 3-D simulator CST-microwave studio. This paper describes the design and simulation of a high performance 35-GHz ${rm TE}_{01}$ mode gyro-TWT that applies the same technique of employing a periodic dielectric loaded interaction structure to achieve stability and wide bandwidth. The stability of this gyro-amplifier is excellent and demonstrates that the ceramic loading is highly effective for suppressing the spurious oscillations in gyro-TWT. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Estimation Method for Self-Impedance's Real Part of Multigap Output Cavity of Klystrons Using Group Delay

    Page(s): 2269 - 2276
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (689 KB) |  | HTML iconHTML  

    A new estimation method by group delay for the real part of the self-impedance of multigap (two or more gaps) output cavity of klystrons is presented. Although these electromagnetic data can be easily obtained by using electromagnetic simulation (e.g., MWS or HFSS), we still need a cold test to confirm and adjust the values because in actual manufacturing, there are several steps that can slightly change the sizes of cavities and the parameters of high frequency. The traditional impedance measurement method for output cavity needs three steps, i.e., open, short, and perturbation, and the problems caused by a multigap cavity in the measurement of middle gaps (excluding the gaps at two sides) will meet difficulties when setting perturbation and short states. Beginning with microwave network theory and aiming at three-gap output cavity, this paper finally establishes the relationship between the group delay and the real part of the self-impedance of the output cavity. Then, the new method is no longer limited by the number of gaps through eliminating the perturbation and the short states of the traditional method. Using the new and traditional methods, a double-gap output cavity of an S-band klystron has been separately measured. Moreover, the feasibility of the method has also been verified by comparing their results. Finally, the relevant results of the five-gap output cavity of an X-band sheet-beam klystron are given. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Study of a Log-Periodic Slow Wave Structure for Ka-band Radial Sheet Beam Traveling Wave Tube

    Page(s): 2277 - 2282
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1205 KB) |  | HTML iconHTML  

    A novel slow wave structure (SWS) named angular log-periodic meander-line is proposed for a radial traveling wave tube (TWT). In this paper, a 30 log-periods microstrip angular log-periodic meander-line SWS is studied. The dispersion of this kind of SWS is weak, which shows that it can work in a wide operating bandwidth. The more important advantage is that the operating voltage is much lower than that of the conventional TWT at the same operating frequency and the geometrical dimension is also much smaller than that of the conventional TWT. The beam–wave interaction of the angular log-periodic meander-line TWT is calculated using the particle-in-cell method. When the operating voltage is 1624 V, this kind of TWT can give 156.5-W output power at 35 GHz, the gain is 21.9 dB, and the electron efficiency is ${sim}17.7%$. With this kind of TWT as mentioned, the concept of radial integrated angular log-periodic meander-line TWT is proposed, which can provide a new way to obtain higher output power. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A High Directive Paraboloidal Reflector Antenna for High Far Voltage in an Ultra Wideband Source System

    Page(s): 2283 - 2290
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1943 KB) |  | HTML iconHTML  

    This paper proposes a paraboloidal reflector-based integrated antenna-source (IAS) system for increasing the strength of radiated electric fields in ultrawideband (UWB) pulses. With the transient analysis of a paraboloidal structure, the reflector for an omnidirectional radiation source is designed. The paraboloidal reflector-based IAS system is structurally uncomplicated and compact. The proposed high power wideband radiator has a peak value of 42.9 kV/m at a distance of 40 m and a center frequency of 1.1 GHz. Thus, the strength of electric field rises by 8.9 times compared with that of the system without reflector. It is numerically and experimentally proved that both the far voltage and the UWB gain are significantly increased. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Simulation of Electron Hop Funnel Hysteresis

    Page(s): 2291 - 2298
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2123 KB) |  | HTML iconHTML  

    Insulating funnels, called electron hop funnels, use secondary electron emission and an electric field created by an electrode to transport current through the device. The surface charge along the funnel wall self-adjusts to get unity-gain transmission. Electron hop funnels allow increased control over the spatial and energy uniformity of the transmitted beam from a field emitter array. Measurements performed on the relationship between transmission through the device and the electrode voltage has shown hysteresis. To better understand the origin of the hysteresis, simulations have been performed using the particle trajectory code Lorentz 2E. The simulations reveal two very important mechanisms that define the transmission through the funnel. The simulations also show that hysteresis is a fundamental characteristic of hop funnels. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Acceleration of Ions by an Electron Beam Injected Into a Closed Conducting Cavity

    Page(s): 2299 - 2312
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2863 KB) |  | HTML iconHTML  

    In a pinched-beam ion diode, an intense electron beam focuses on-axis at the center of the anode and passes through the thin anode foil into a beam dump region behind the anode foil. The beam dump usually consists of an evacuated cylindrical anode-can. Because of energy deposition from the intense electron beam, the interior surfaces of the anode-can are expected to be space-charge-limited emitters. Therefore, the electron space charge from the beam in the anode-can will draw ions off these surfaces. There is evidence from nuclear activation which suggests that ions exist in the anode-can with energies that significantly exceed those associated with the diode voltage. Analysis and particle-in-cell simulations show that a virtual cathode can form in the anode-can that accelerates ions up to the energy associated with the diode voltage. Additionally, a subset of these ions can form current bursts that are driven to the outer wall of the anode-can with ion energies as high as a few times the energy associated with the diode voltage. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the Active Species Concentrations of Atmospheric Pressure Nonequilibrium Plasma Jets

    Page(s): 2313 - 2326
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3268 KB) |  | HTML iconHTML  

    Atmospheric pressure nonequilibrium plasma jets (APNP-Js), which generate plasma in open space rather than in a confined discharge gap, are recently a topic of great interest. However, researchers actually know little about the bright plasma plume in the beginning. Fortunately, after about one decade of researches, the main active species concentrations of APNP-Js are measured. Although the measurements are carried out for different plasma jet devices and under different experimental conditions, it still gives us some insight information about the plasma plumes. In this paper, the measurements on the concentrations of the main active species such as electron, O atom, OH, ${rm O}_{2}(^{1}Delta_{g})$, metastable state He and Ar, nitric oxide (NO), metastable state ${rm N}_{2}({rm A}^{3}Sigma_{u}^{+})$, and N atom for different experimental conditions are reviewed. The peak electron density of a microplasma plume could reach in the order of $10^{14}~{rm cm}^{-3}$. The O atom density is in the order $10^{14}~{rm cm}^{-3}$ in the plasma plume but it is in the order $10^{16}~{rm cm}^{-3}$ inside the discharge gap. The OH and ${rm O}_{2}(^{1}Delta_{g})$ densities are in the order of $10^{15}~{rm cm}^{-3}$. The metastable state He and Ar concentrations could reach the order of $10^{11}$ and $10^{12}~{rm cm}^{-3}$, respectively. The NO density is in the order of $10^{15}~{rm cm}^{-3}$ in the plasma plume. It should be emphasized that all the measurements are carried out under different experimental conditions and for different experimental setups. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Influence of Rise Rate of Applied Voltage for Water Treatment by Pulsed Streamer Discharge in Air-Sprayed Droplets

    Page(s): 2327 - 2334
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1076 KB) |  | HTML iconHTML  

    This paper investigates a water treatment method of spraying droplets of wastewater into a pulse discharge space. Water treatment is performed by applying a pulsed voltage with different rise rates to investigate the influence of rise rate. The rise rates of the applied voltage are 1300, 830, and 240 V/ns, and the discharge current in the faster rise rates is higher. The plasma diameter of the streamer discharge is believed to increase with an increase in the rise rate. The treatment is applied to an aqueous solution of indigo carmine. Active species, e.g., ozone and OH radicals, generated by the discharge increase owing to the effect of a higher rise rate. Therefore, the chromogenic bond of the indigo carmine is decomposed more rapidly with a higher rise rate. The decomposition speed of the benzene ring of the indigo carmine is, however, similar because the more OH radicals there are, the shorter their lifetime is. The energy efficiency for the decomposition of the indigo carmine depends on the discharge power and the discharge duration, which varies owing to the difference of the rise rate. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Parameters Identification and Gas Behavior Characterization of DBD Systems

    Page(s): 2335 - 2342
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1913 KB) |  | HTML iconHTML  

    This paper proposes an efficient modeling and an identification method for dielectric barrier discharge (DBD) systems, based on input–output (current–voltage) experimental measurements. The DBD is modeled using an equivalent electric circuit associated with a differential equation that describes the dynamics of its conductance. This equation assumes a homogeneous behavior of the gas. This paper introduces a series of polynomial terms of the current of the gas into the conductance equation. These terms, after identification, are a very useful tool to analyze the physical mechanisms that take place in the gas. The identification process also returns the numerical values of other DBD parameters, such as associated capacitances and the breakdown voltage. In addition, an asymmetric model for the gas, which considers the direction of the current, is proposed to consider the possible geometrical dissimilarity between the two electrodes of the DBD setup. Experimental measurements taken on two different DBD applications are used for validating the proposed approach. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Study on High-Luminance Sustain Pulses Using Consecutive Second Emission in AC-PDP

    Page(s): 2343 - 2348
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1628 KB) |  | HTML iconHTML  

    In this paper, four different sustaining pulses are examined and their electrical and emissive characteristics are compared with those of the conventional pulse. For a comparative study, an infrared emission, luminance, and discharge current during the sustaining period are measured. A distinguishable second emission is observed after the ignition of sustaining discharge and during infrared measurements with the photometer and an intensified charge-coupled device. This is the main reason for enhancing the luminance during the sustaining period. One of the proposed pulses shows a stronger second emission than the other pulses. Its luminance is 25% and its efficiency is 47.3% higher than those of the conventional pulse. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of Pulsed Power on Particle Matter in Diesel Engine Exhaust Using a DBD Plasma Reactor

    Page(s): 2349 - 2358
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1981 KB) |  | HTML iconHTML  

    Nonthermal plasma (NTP) treatment of exhaust gas is a promising technology for both nitrogen oxides $({rm NO}_{rm X})$ and particulate matter (PM) reduction by introducing plasma into the exhaust gases. This paper considers the effect of NTP on PM mass reduction, PM size distribution, and PM removal efficiency. The experiments are performed on real exhaust gases from a diesel engine. The NTP is generated by applying high-voltage pulses using a pulsed power supply across a dielectric barrier discharge (DBD) reactor. The effects of the applied high-voltage pulses up to 19.44 kVpp with repetition rate of 10 kHz are investigated. In this paper, it is shown that the PM removal and PM size distribution need to be considered both together, as it is possible to achieve high PM removal efficiency with undesirable increase in the number of small particles. Regarding these two important factors, in this paper, 17-kVpp voltage level is determined to be an optimum point for the given configuration. Moreover, particles deposition on the surface of the DBD reactor is found to be a significant phenomenon, which should be considered in all plasma PM removal tests. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • {\rm CO}_{2} as an Arc Interruption Medium in Gas Circuit Breakers

    Page(s): 2359 - 2369
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1121 KB) |  | HTML iconHTML  

    ${rm CO}_{2}$ is a possible alternative to ${rm SF}_{6}$ —which has a high global warming potential—as the interruption medium in gas circuit breakers. The performance of ${rm CO}_{2}$ is investigated in this paper by carrying out experiments in representative test devices and by performing computational fluid dynamic (CFD) simulations; some comparisons with ${rm SF}_{6}$ and air are given. It is found that the thermal interruption performance of ${rm CO}_{2}$ is lower than that of ${rm SF}_{6}$, but higher than that of air. The measured dielectric recovery after arcing is compared for ${rm CO}_{2}$ and ${rm SF}_{6}$; a streamer model is used to calculate the breakdown voltage in ${rm CO}_{2}$; good agreement with measurement is found. The speed of sound and the adiabatic coefficient, important parameters that influence pressure buildup and gas flow, are compared for ${rm SF}_{6}$, ${rm CO}_{2}$, and air. CFD simulations of the pressure buildup in ${rm CO}_{2}$ and ${rm SF}_{6}$ both illustrate the qualitative differences between the two and show good agreement with measurements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Pebrine Disease of Chinese Silkworm Controlled by Using Atmospheric Cold Plasma Jet

    Page(s): 2370 - 2376
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2707 KB) |  | HTML iconHTML  

    Tussah pebrine disease resulting from Nosema bombycis (NB) spores causes massive production and economic losses in the silk industry in China. This paper reports on highly effective inactivation of NB spores for the control of pebrine disease by using an atmospheric pressure cold plasma jet. Both Giemsa dyeing measurement and tussah breeding experiment show that the atmospheric pressure He plasma jet containing 1% ${rm O}_{2}$ kills almost all the NB spores with a $10^{7}$ population within an exposure time of 5 min. Scanning electron microscopy measurements and UV absorbance spectra show that plasma inactivation has withered up the NB spores and resulted in the spores inactivated. Both energy dispersive spectroscopy and optical emission spectroscopy measurements showed that plasma-created reactive particles, such as O and accompanied charged species can play an important role in the inactivation processing. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Study on the Addressing Characteristics of an ac PDP With Sc-Doped MgO-Protecting Layer

    Page(s): 2377 - 2380
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (439 KB) |  | HTML iconHTML  

    In this paper, the addressing characteristics of an ac plasma display panel (PDP) with Sc-doped MgO-protecting layer are investigated. The characteristics of addressing voltage and temporal distribution of addressing discharge event in Sc-doped MgO panel are different from those in a conventional MgO panel. In particular, the characteristics depending on the operation temperature are changed drastically in Sc-doped MgO panel. The formative discharge time lag increases as the addressing pulse application time and operation temperature increase regardless of protecting layers. The statistical time lag shows the contrary trend compared to the formative discharge time lag except for the MgO when operated in room temperature. The variation of addressing voltage and temporal distribution of addressing discharge event in different protecting layers can be understood through the survey of previous research result on the exoelectron emission characteristics from protecting layers in an ac PDP. It is assumed that the emission of electrons from a protecting layer results in the decrease of wall voltage but increase of priming effect for the addressing discharge. Also, the possibility for the control of addressing characteristics is suggested by changing scan voltage level during address period. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of Plasma and UV Radiation of Multigap Sliding Discharge in Air on Bacteria

    Page(s): 2381 - 2386
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1707 KB) |  | HTML iconHTML  

    The device generating pulsed-periodic multigap sliding discharges in air was used to study the impact of plasma and UV radiation on bacterial test objects, which were prepopulated with bacteria Escherichia coli (Ec) and Staphylococcus aureus (Sa). Bactericidal effect was revealed, which varied depending on period of impact, distance, and exposure time. It is found that Sa bacteria were less resistant to plasma and UV treatments than Ec bacteria. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electronegativity of Hollow Cathode DC Discharge in {\rm O}_{2} Employing Electrostatic Probe Diagnostics

    Page(s): 2387 - 2393
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (852 KB) |  | HTML iconHTML  

    Electron temperature and number density are investigated employing hollow cathode dc discharge in ${rm O}_{2}$. Electron temperature is found to decrease from 3 to 1.85 eV as the pressure increases from 75 to 375 mTorr. Positive and negative ion densities are determined as a function of plasma gas pressure. $I{-}V$ curves are evaluated employing the Allen–Boyd–Reynolds (ABR), current balance, orbital motion limited, and the floating potential (FP) methods. The ABR method is found to yield the highest positive ion number density, whereas the FP method results for $n_{+}$ are extremely small for any meaningful data. Present results are compared to those obtained employing global simulation method as well as with other experimental groups. ${rm O}_{2}$ electronegativity results are compared with other experimental and theoretical groups. Optical emission spectroscopy is employed and intensity ratio for the 777 and 845-nm lines is obtained for comparison with other groups concluding that ${rm O}^{-}$ is the dominant species. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Control of the Plasma Characteristics by Hot Limiter Biasing in the IR-T1 Tokamak

    Page(s): 2394 - 2399
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (642 KB) |  | HTML iconHTML  

    A tokamak's plasma characteristics as well as plasma modes are analyzed in the presence of hot limiter biasing regime in the IR-T1 Tokamak. Fast Fourier transform analysis is a reliable technique for mode detection in tokamaks. For this purpose, we use a poloidal array of Mirnov coils and hot limiter biasing system. After Fourier analysis on Mirnov coils data in the presence of hot biased limiter, power spectral density (PSD) diagram is plotted. PSD describes how the power of a signal is distributed with frequency. We obtain the maximum MHD activity using power spectrum in the frequency of 33 kHz. In this contribution, we also determine edge safety factor and safety factor from Fourier-based derived mode numbers $q=m/n$. The edge safety factor was determined to be smaller than 3, and the values of obtained safety factor from the mode numbers are between $2leq qleq 5$. Results show that hot limiter biasing with appropriate conditions can be used for control of the plasma safety factor and other plasma characteristics. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Parametric Study of the Current–Voltage Characteristics of a 100-mbar DC Discharge in Argon: From the Diffuse Glow Discharge to the Arc Regime

    Page(s): 2400 - 2407
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1316 KB) |  | HTML iconHTML  

    The aim of this paper is to investigate the glow discharge in its diffuse and filamentary regime, and to study its transition to arc in argon at 100 mbar. The structure of the discharge is observed in correlation with its electrical signals in both static and in dynamic modes. Glow discharges were identified with a positive column that can be fully diffuse, fully filamentary, or a mix of the two with the filamentary part of the column always attached to the anode. Spontaneous transitions between glow discharges and arcs have also been observed and their dynamics are studied. Using high-speed imaging, the transition between glow and arc discharge was identified as the occurrence of two distinct phenomena: a propagation mechanism in the positive column and a constriction of the cathode root. An evaluation of the duration of each phenomenon as a function of electrode gap and current intensity was obtained. The duration of the constriction of the cathode root is found to be on the order of tens of nanoseconds and the duration of the propagation mechanism in the range 50–550 ns. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

IEEE Transactions on Plasma Sciences focuses on plasma science and engineering, including: magnetofluid dynamics and thermionics; plasma dynamics; gaseous electronics and arc technology.

 

 

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Steven J. Gitomer, Ph.D.
Senior Scientist, US Civilian Research & Development Foundation
Guest Scientist, Los Alamos National Laboratory
1428 Miracerros Loop South
Santa Fe, NM  87505  87505  USA
tps-editor@ieee.org
Phone:505-988-5751
Fax:505-988-5751 (call first)