Filling Gas Pressure Research Articles

The Effect of Accumulator Volume and Inflation Pressure on Tracked Vehicle Braking System

Based on the braking system of a tracked vehicle, a method for co-simulation is introduced with dynamic simulation software ADAMS and multidisciplinary dynamic simulation software EASY5. By designing software interface, dynamic data exchange between the two models is achieved, and the simulation is carried out about the impact on a tracked vehicle brake performance with accumulator volume and gas-filled pressure. The simulation result shows that a seamless connection between the virtual prototype model and hydraulic system model is realized.

Role of static inductance on ion beam emission in plasma focus devices

AbstractThe role of static inductance on ion beam emission in plasma focus devices, based on anomalous resistivity, is reported. The effect of gas pressure variation on the process of energy transfer into plasma is investigated and discussed by using Lee's model. The dependence of ion beam production on filling gas pressure along with change in static inductance is studied. The results show that increase of static inductance in a specific range of operating pressure can enhance the efficiency of dense plasma focus device.

Mode transition in magnetic pole enhanced inductively coupled argon plasmas

The electrical probe (Langmuir probe) diagnostics of different plasma parameters and operation regimes (E/H modes) of magnetic pole enhanced, inductively coupled (MaPE-ICP) argon plasmas are investigated. It is shown that uniform, high density (ne ∼ 1012 cm-3) and low electron temperature (Te ∼ 1.5 eV) plasma can be produced in low pressure argon discharges at a low power (100 W). It is found that an MaPE-ICP reactor operates in two different modes; capacitive (E mode) and inductive (H mode). No density jump or hysteresis are reported between these modes. The effect of pressure on transition power, where the mode changes from E to H mode at 20 sccm gas flow rate are studied and it is found that for all pressures tested (∼7.5 mTorr to 75 mTorr) the transition power remains same. In the inductive mode, the above plasma parameters show a smooth variation with increasing filling gas pressure at fixed power. The intensity of the emission line at 750.4 nm due to 2p1 → 1s2 (Paschen’s notation) transition, closely follows the variation of ne with RF power and filling gas pressure. Measured electron energy probability function (EEPF) shows that electron occupation mostly changes in the high-energy tail, which enlightens close similarity of the 750.4 nm argon line to electron number density (ne). The behaviour of the electron energy probability function (EEPF) with regard to pressure and RF power in two operational modes is presented.

Investigation of long-range temporal correlation in electron cyclotron resonance produced linear magnetized plasma of the MaPLE device

Long range temporal correlation of the low frequency fluctuations is investigated in a linear electron cyclotron resonance produced magnetized plasma at different radial positions and filling gas pressures. These fluctuations turn from chaotic to coherent and again chaotic as one moves radially outwards from the center towards the edge region. The power spectrum of these fluctuations shows three distinct frequency regions characterized by their power exponents. Long range temporal correlation of these fluctuations is investigated by estimating the self similarity parameter (Hurst exponents) using rescaled range (R/S) statistics as well as from power spectrum analysis. Dependence of this long range temporal correlation on filling gas pressure has also been investigated.

Correlation of current drop, filling gas pressure, and ion beam emission in a low energy Mather-type plasma focus device

The behavior of current drop and its correlation with ion beam emission during the radial phase of a high inductance low energy Mather type plasma focus device have been studied. The study includes two ranges of filling gas pressure, namely the low range of 0.2–0.8 mbar and the high range of 0.8–1.5 mbar. Two different current simulation processes were performed to aid the interpretation of the experimental results. Within the low range of operating pressure, an acceptable match between the computed and experimental current signals was achieved when the effects of anomalous resistances were contemplated. While in the high range of pressure, the computed and experimental current traces were in line even without considering the effects of anomalous resistances. The analysis shows that by decreasing the filling gas pressure the effects of instabilities are intensified. The computed and experimental current traces, along with ion beam signals gathered from a faraday cup, show that there is a strong correlation between the intensity of ion beam and its duration with the current drop during the radial phase.

High Performance High Repetition Rate Miniature Plasma Focus Device: Record Time Averaged Neutron Yield at 200 J with Enhanced Reproducibility

A high performance high repetition rate plasma focus device with significant time averaged neutron yield and greater shot to shot reproducibility could be a highly valuable neutron source for Homeland Security applications. The single module fast miniature plasma focus ‘FMPF-2’ (2.4 μF, 56 ± 3 nH, 89 kA @ 14.0 kV, T/4~575 ns) was upgraded to four module ‘FMPF-3’ (2.4 μF, 34 ± 2 nH, 103 kA @ 14.0 kV, T/4~458 ns) device. The time averaged neutron output of (1.4 ± 0.6) × 106 n/sec at 1 Hz operation was enhanced to the record value of (1.4 ± 0.2) × 107 n/sec at 10 Hz operation for the burst length of 50 consecutive shots for deuterium filling gas pressure of 5.5 mbar in FMPF-3 device at storage energy of ~200 J. Other key findings of the investigation were: (i) the deuterium filling gas pressure for single shot and repetitive modes of device operation were needed to be optimized separately, and (ii) in the repetitive mode of operation the deuterium filling gas pressure was higher than that obtained for single shot mode and also yielded better reproducibility in neutron emission.

Anomalous resistivity effect on multiple ion beam emission and hard x-ray generation in a Mather type plasma focus device

Multi ion beam and hard x-ray emissions were detected in a high inductance (more than 100 nH) Mather type plasma focus (PF) device at different filling gas pressures and charging voltages. The signal analysis was performed through the current trace, as it is the fundamental signal from which all of the phenomena in a PF device can be extracted. Two different fitting processes were carried out according to Lee’s computational (snow-plow) model. In the first process, only plasma dynamics and classical (Spitzer) resistances were considered as energy consumer parameters for plasma. This led to an unsuccessful fitting and did not answer the energy transfer mechanism into plasma. A second fitting process was considered through the addition of anomalous resistance, which provided the best fit. Anomalous resistance was the source of long decrease in current trace, and multi dips and multi peaks of high voltage probe. Multi-peak features were interpreted considering the second fitting process along with the mechanisms for ion beam production and hard x-ray emission. To show the important role of the anomalous resistance, the duration of the current drop was discussed.

Influence of Pyrex Insulator Thickness and it’s Length on Hard X-Ray Intensity in APF Plasma Focus Device

In order to improve the HXR emission from APF plasma focus device we have investigated the effect of insulator sleeve outer diameter (O.D.) and its length. Fourteen different insulator sleeve geometries at three different filling gas pressures of 6, 7 and 8 Torr of neon are used in the present investigation. The average HXR yield, measured using scintillation detector, has been found to increase with the increase in insulator sleeve O.D. from 31 to 34 mm. Further increase in insulator sleeve diameter to 37 mm, however, decreased the HXR yield. The highest magnitude of 234.5 kA was achieved for 34 mm O.D. of sleeve at filling gas pressure of 7 Torr and voltage of 12 kV.

X-Ray Measurement and Enhancement of SBUPF1 Plasma Focus Device in Different Ar Pressures and Operating Voltages

In this paper, best condition of filling gas pressure and operating voltage for SBUPF1 plasma focus device to have maximum intensity of hard and soft X-ray emission has been reported. For time resolved X-ray detection, PIN detector and fast plastic Scintillator detector with appropriate filters have been used and for time integrated X-ray emission measurement, radiography films with appropriate filter masks have been used. Rogowski coil has been used for pinch detection. The highest hard X-ray emission has been observed at the pressure of 0.45 mbar of Argon and discharge voltage about 23.5 kV. The highest Soft X-ray emission has been observed at the pressure of 0.35 mbar of Argon and discharge voltage about 23.5 kV. For enhancement of hard X-ray emission intensity, lead disk was placed in copper anode tip and measurements were repeated. Results have shown that hard X-ray emission has been enhanced about 23% and soft X-ray emission has been enhanced about 33% with inserting a high atomic number metal disk like lead. Results from integral X-ray measurement have shown presence of dominant peaks in ranges 13.2–15, 21–21.9 and 23.4–24.3 keV with significant spectral components in the range of 0–50 keV. Pinch size has measured with pin hole camera and it is about 0.6 mm × 2.12 mm. Captured images with SBUPF1 have confirmed that it is a suitable source for introspective imaging with capability of showing very fine details.

SYMMETRIC AND ASYMMETRIC DOUBLE LANGMUIR PROBES CHARACTERIZATION OF RADIO FREQUENCY INDUCTIVLEY COUPLED NITROGEN PLASMA

The symmetric and asymmetric double Langmuir probe systems with their necessary driving circuits are developed for characterization of low pressure inductively coupled nitrogen plasma, generated and sustained with 13.56 MHz RF source and an automatic impedance matching network. First of all, the plasma parameters such as ion saturation current, electron temperature and electron number density are determined with symmetric double probe system at different input RF powers, filling gas pressures and radial distance Received 4 March 2011, Accepted 28 March 2011, Scheduled 30 March 2011 Corresponding author: Muhammad Yasin Naz (yasin603@yahoo.com).

The Performance Analysis of Electro-Rheological Damper

Electro-Rheological (ER) fluid is a smart material. It develops a new path for automotive semi-active intelligent suspension system. The damping force of ER damper can be controlled by applied electric field. Applying the theory of rheodynamics and hydraulic theory, a relationship of damping vs. vibration velocity, electric field strength and gas-filled pressure has been set up. There are three sections of damping force, background damping force of a fluid viscosity, electric damping force of applied electric field and pressure of gas. A new gas-filled ER damper is developed. The main structure parameter of influencing ER damper performance are discussed, some design principles of ER damper are given.

Bifurcation of the plasma turbulence on LMD-U

Density fluctuation spectra are qualitatively modified depending on filling gas pressure and magnetic field strength in a linear magnetized plasma. Abrupt and spontaneous jumps between fluctuation states during a discharge are observed in the filling gas pressure–magnetic field plane. Those jumps are characterized using a spectrum pattern and have a bifurcation property on the plane.

Fuelling characteristics of supersonic molecular beam injection in JT-60U

Supersonic molecular beam injection (SMBI) was successfully operated in JT-60U after improving the performance of the vacuum seal used inside the injector head. Frequent density jumps were clearly observed in the main plasma against the SMBI pulses with filling gas pressures (PFG) of 0.2–0.6 MPa. The fuelling efficiency exhibited a weak dependence on PFG and the injection direction (high- and low-field-side injections). The amount of fuelling necessary for achieving the same density level is much smaller for SMBI than for gas puffing. It is comparable for SMBI and pellet injection even with shallower penetration of SMBI as discussed. The SMBI ionization area was estimated based on emission measured using a fast TV camera with a time resolution of 0.167 ms. The estimations indicated a similar penetration position for PFG = 0.6 and 0.2 MPa, although the ionization area was larger for 0.6 MPa. This result supports the weak PFG dependence of the fuelling efficiency. The front of the ionization area moved between the first and second frames of the fast TV camera and it reached just inside the separatrix in the second frame. The ionization area was significantly expanded even in the first frame from the expected SMB size and the expansion was enhanced in the second frame. These relatively slow changes between the two frames suggest that the interaction between the SMB and the plasma significantly influences the fuelling characteristics.

Ion Beam Emission within a Low Energy Focus Plasma (0.1 kJ) Operating with Hydrogen

An investigation of energetic ion beam emission from a low energy plasma focus (0.1 kJ Mather type) device operating with hydrogen gas is studied. The ion beam emission is investigated using time-integrated and time-resolved detectors. The present plasma focus device is powered by a capacitor bank of 1 μF at 18 kV maximum charging voltage. The correlation of ion beam intensity with filling gas pressure indicates that the beam emission is maximized at the optimum pressure for the focus formation at peak current. Energy of ions is determined with a time-of-flight (TOF) method, taking into account distance from the center electrode to the detection plane.

A Physically Based Fluorescent Lamp Model for a SPICE or a Simulink Environment

This paper describes a method of modeling fluorescent lamps. The lamp model can be implemented in all major circuit simulation software packages, an example has been given for SPICE and Simulink. The model is based upon a simplified set of physical equations that gives the model validity over a wider range of operating conditions than current fluorescent lamp SPICE models allow for. The model can be used to model any low-pressure mercury-buffer gas fluorescent lamps by entering key lamp parameters, length, radius, cold-spot temperature, and buffer gas fill pressure. If fill pressure is not known, a default value dependent on lamp radius is used. The model shows good agreement over a wide range of operating frequencies and lamp powers.

Nanostructured magnetic CoPt thin films synthesis using dense plasma focus device operating at sub-kilojoule range

A repetitive NX2 dense plasma focus (DPF) device, operating at a low voltage of 8 kV with a stored energy of capacitor bank in the sub-kilojoule range (∼880 J), was successfully used to deposit nanostructured magnetic CoPt thin films. The samples were synthesized at different filling hydrogen gas pressures and using different numbers of plasma focus deposition shots. The size of agglomerates/nanoparticles and the thickness of the CoPt thin films depend strongly on the filling gas pressure and the number of plasma focus deposition shots; hence it provides a possibility to control the CoPt agglomerates/nanoparticles size and the deposition rate by simply changing the operating parameters of the DPF system. The typical deposition rate of nanostructured CoPt thin film in the DPF device is much higher as compared with that of conventional PLD. The as-deposited CoPt nanoparticles are in the magnetically soft fcc phase and an annealing temperature of about 600 °C is required for phase transition to the magnetically hard fct phase, which may find possible applications in high density data storage.

Generation and application of high energy, 30 fs pulses at 527 nm by hollow-fiber compression technique

The compression of laser pulses at 527 nm, 250 fs long, down to 30 fs is reported. The laser pulses, originated from a frequency-doubled, mode-locked Nd:glass laser, were compressed by a 0.7-m-long, 150-μ m-bore-diameter argon-filled hollow fiber and a pair of SF10 prisms with a final energy of 160 μJ. These are the shortest, high energy pulses ever produced by direct pulse compression at the central wavelength of 527 nm. The spectral broadening of the pulses propagating inside the hollow fiber was experimentally examined for various filling-gas pressures and input pulse energies. The physical limitations of the hollow-fiber pulse compression technique applied in the visible range are also studied. An application to laser ablation of Ni target is performed. Metal nanoparticles are obtained both with the 250-fs and with the 30-fs pulse.

Self-consistent three-dimensional modeling and simulation of large-scale rectangular surface-wave plasma source

A self-consistent and three-dimensional (3D) model of argon discharge in a large-scale rectangular surface-wave plasma (SWP) source is presented in this paper, which is based on the finite-difference time-domain (FDTD) approximation to Maxwell's equations self-consistently coupled with a fluid model for plasma evolution. The discharge characteristics at an input microwave power of 1200 W and a filling gas pressure of 50 Pa in the SWP source are analyzed. The simulation shows the time evolution of deposited power density at different stages, and the 3D distributions of electron density and temperature in the chamber at steady state. In addition, the results show that there is a peak of plasma density approximately at a vertical distance of 3 cm from the quartz window.

Experimental study of neutron emission characteristics in a compact sub-kilojoule range miniature plasma focus device

In order to gain insight into the possible neutron production mechanism in sub-kilojoule miniature plasma foci, the anisotropy in neutron and hard x-ray emissions from a newly developed fast miniature plasma focus device (2.4 µF, 27 nH, T/4 ∼ 400 ns, 12–15 kV, 170–270 J, total mass ∼25 kg) is investigated. The system produces an average neutron yield of (1.2±0.2) × 106 neutrons/shot into 4π sr at ∼80 kA peak discharge current and 5.5 mbar deuterium operation, as measured by a 3He proportional counter. Relative measurements of radiation yields, to gauge the emission anisotropy, have been performed using a pair of fast scintillator–photomultiplier detectors placed along the axial (0°) and radial (90°) directions. The average forward to radial neutron yield anisotropy is found to be 1.3±0.2. The average peak neutron energy for the axial and radial directions is estimated to be (2.9±0.3) MeV and (2.6±0.1) MeV, respectively. The observed higher fluence along the anode axis and the coincidence between occurrence of maximum neutron yield and anisotropy at 5.5 mbar deuterium filling gas pressure, suggest that the neutron production mechanism in the sub-kilojoule range miniature plasma focus device FMPF-1 may be predominantly beam–target in nature.

Mercury-free electrodeless discharge lamp: effect of xenon pressure and plasma parameters on luminance

Since there is much concern about environmental preservation, the authors have paid attention to the uses of mercury in lighting application. They have focused on the application of the xenon low-pressure inductively coupled plasma (ICP) discharge in developing cylindrical type mercury-free light sources. ICP can be operated at low filling gas pressures and demonstrates significant potential in producing high density plasma. Xenon pressure was varied from 0.1 to 100 Torr and the lamp luminance was measured. The gas pressure dependence shows an increase in luminance at pressures below 1 Torr. In order to clarify this behaviour, measurement of plasma parameters was carried out using the double probe method and its relation to lamp luminance is discussed. As the gas pressure is decreased (from 1 to 0.01 Torr), the electron temperature increases while the electron density decreases while at the same time the lamp luminance increases. There are several factors that are believed to contribute to the increase in luminance in the very low pressure region. Increases in luminance are considered to be due to the electron–ion recombination process which brings a strong recombination radiation in continuum in the visible region and also due to the effect of stochastic heating.