The influence of longitudinal magnetic field on recombination radiation of low-pressure glow discharge in hydrogen and helium

We study the influence of longitudinal magnetic field on the radiation of low-pressure glow discharges in hydrogen and helium. We conducted experiments under a pressure in a discharge chamber of 10–20 Pa and a discharge current of 10–20 mA. A 0–1600 G magnetic field influenced only the cathode parts of the discharge, negative glow, and the dark Faraday space. The electron temperature and density were measured by the two-probe method as a function of magnetic field. We studied the dependence of the intensity of radiation in the spectral lines and continuous spectrum on magnetic field induction. We discovered that, under the action of magnetic field, discharge in hydrogen and helium is compressed and its glow volume increases by a factor of 20–25. In contrast, the radiation intensity in the lines and continuous spectrum increase by a factor of 100–200. We found a strong discrepancy in the measured intensity of the continuous spectrum into spectral ranges with calculation of electron-ion recombination.     

Effect of a magnetic field on ionizing electric discharge in air

We have studied the effect of an external magnetic field on the form and structure of high-voltage gas discharge used for the ionization of airflow to the degree (∼10⁻⁵) necessary for the creation of a magnetohydrodynamic (MHD) control system. The experimental setup based on a shock tube comprised a magnetic field generation system, a 2–4 μs-pulsed, high-voltage, ionizing discharge system and an expanding MHD channel with a set of electrodes oriented along and across the magnetic field. In the first series of experiments, the discharge current was closed along the magnetic field lines; in the second series, the current was closed in the transverse direction. The patterns of discharge glow at various values of the magnetic induction were monitored. It is established that the most effective configuration employs periodic pulsed ionizing discharge in the transverse direction and a system of electrodes closing the magnetic-field-induced current.     

Formation of coulomb clusters from charged diamagnetic microparticles in inhomogeneous magnetic field

The possibility of levitating Coulomb clusters formed by charged diamagnetic microparticles in an inhomogeneous magnetic field has been theoretically substantiated and experimentally confirmed. An experimental setup is described, in which the Coulomb clusters can be formed from charged graphite particles 100–300 μm in size and maintained stable between the poles of an electromagnet generating a magnetic field with induction B ∼ 10⁴ G and gradient |∂B| ∼ 10⁵ G/cm.     

Influence of the electric field on the soot formation in the flame at a low pressure

We have investigated the influence of an electric field in the form of a gas discharge on the flame pattern, the radiographic parameters of soot particles, and the yield of fullerenes and polycyclic aromatic hydrocarbons. It has been shown that an external electric field permits controlling the processes proceeding in the flame, as well as the soot formation, and even increasing the soot yield under certain conditions. It has been established that the height of the soot packet L _c and the interplanar spacing d ₀₀₂ remain unchanged with increasing voltage, which is confirmed by the absence of graphitization under the action of the electric field. It has been revealed that negative polarity has a stronger effect on the increase in the yield of fullerenes with increasing voltage applied compared to positive polarity.     

Influence of interelectrode gap and magnetic induction on the voltage of an electric arc moving in air under the action of a magnetic field

For arcs that are initiated in an air medium in rotation in a ventilated annular gap and move along parallel electrodes under the action of an external magnetic field, the influence of the magnitude of the interelectrode gap and magnetic induction on the discharge voltage is considered. The accuracy of the volt-ampere characteristics of the arc in approximating by means of simple empirical power formulas and with the use of criterial relations between generalized variables is estimated. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 3, pp. 469–475, May–June, 1997.     

Characteristics and plasma parameters of a short-wavelength low-pressure discharge lamp

We have studied the working optical characteristics and electron kinetic coefficients of a short-wavelength, electric discharge exciplex-halogen UV-VUV lamp employing a mixture of argon and chlorine with a total pressure of P = 0.5–10 kPa. The lamp operates on a system of broadened electron-vibrational bands of ArCl (175 nm) and chlorine (200, 258 nm) molecules, which overlap to form a continuum in the spectral range of 160–260 nm. It is established that the optimum mixtures are those with p(Ar) − p(Cl₂) = (2–4)−(0.15–0.30) kPa. The average output power of the short-wavelength radiation is 1–2 W at an efficiency of ∼5%. The electron energy distribution functions (EDFs) and the discharge plasma parameters have been calculated by solving the Boltzmann equation for a gas mixture with the experimentally determined optimum composition in the range of E/P values from 1 to 200 V/(cm Torr), where E is the electric field strength and P is the total gas pressure. Using the obtained EDFs, the electron transport characteristics, specific discharge power losses for the main elementary processes, and rate constants of electron processes are determined.     

Initial stage of gas discharge in an inhomogeneous electric field

A model of the initial stage of gas discharge has been developed within the framework of the particle in cell (PIC) method, with allowance for the space charge and particle collisions described using the Monte Carlo (MC) numerical simulation technique. The PIC/MC simulations of the initial stage of discharge under conditions of the electric field strength to gas pressure ratio E/P > 1 kV/(cm Torr) showed that a beam of runaway electrons is formed within ∼10 ps near the cathode, which consists of both emitted electrons and those generated as a result of the gas ionization. The duration of the beam pulse is determined primarily by plasma screening of the external electric field near the cathode and amounts to 10–20 ps.     

Effective transformation of the energy of high-voltage pulses into high-frequency oscillations using a saturated-ferrite-loaded transmission line

A new method of converting a high-voltage video pulse into high-frequency oscillations using a nonlinear transmission line with temporal dispersion has been studied. The dispersion was provided by pulsed magnetization reversal in a ferrite, which was initially magnetized to saturation in an external magnetic field. For a 9-ns pulse, an average energy conversion efficiency of about 10% was achieved. It is demonstrated that oscillations at frequencies within 600 MHz-1.1 GHz with a spectral width of about 15% (at a −3 dB level) can be excited using voltage pulses with an amplitude of 110–290 kV. The optimum bias magnetization fields are within 20–40 kA/m.     

Influence of energy contributions to a high-voltage atmospheric-pressure discharge on the efficiency of conversion of ethanol

The results of experimental investigations of the conversion of ethanol in a high-voltage atmospheric-pressure discharge have been presented. The influence of the energy parameters of the discharge on the yield and energy cost of conversion products has been investigated. It has been established that the minimum energy cost of hydrogen is possible in regimes of discharge burning with a maximum degree of nonequilibrium of the plasma. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 6, pp. 3–6, November–December, 2006.     

Structure and Features of the Motion of a Cathode Spot on a Continuous Titanium Cathode

High-speed video filming by the VS-FAST-NG CCD-array-based video camera from the firm of Videoskan with speeds of 1000 and 5000 frames per second and exposure time of 1·10⁻³ and 2·10⁻⁴ sec, respectively, is conducted. It is established that the arc burns from two or three cathode spots for (1–1.2)·10⁻³ sec. The mean and local speeds of the group of cathode spots are determined. If there is no external magnetic field present, the mean speed is equal to 5–6 m/sec. If there is a magnetic field B = 0.005 T present, the mean speed is equal to 15–16 m/sec. __________ Translated from Izmeritel'naya Tekhnika, No. 10, pp. 42–44, October, 2005.     

Rheological behavior of oils in a magnetic field

The influence of magnetic treatment parameters on the rheological properties of oils has been investigated. It has been noted that the strongest effect on these properties is produced by the regime of magnetic treatment — steady-state or flowing, the volume rate of oil flow, and the induction value of the magnetoactivator magnetic field. The optimal regimes of magnetic treatment have been determined. It has been shown that treatment of oil with a magnetic field promotes a decrease in the solidification temperature and the amount of asphalt-resin deposits. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 1, pp. 102–109, January–February, 2006.     

Influence of the operating regimes of a plasmachemical reactor on the efficiency of conversion of ethanol

The results of experimental investigations on optimization of the process of conversion of ethanol in a high-voltage atmospheric-pressure discharge have been presented. The influence of the structural features of the reactor on the yield and energy cost of conversion products has been investigated. The reactors’ operating regimes ensuring the maximum values of the specific output and the minimum values of the energy cost of hydrogen have been established. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 6, pp. 7–10, November–December, 2006.     

Electric-field-induced dielectric response and magnetization in nano–microscale lead-free multiferroic composite

A new kind of nano/microscale lead-free multiferroic composite with a formal of 0.4CoFe₂O₄–0.6[0.948(K_0.5Na_0.5)NbO₃–0.052LiSbO₃] was prepared. The electric-field-induced dielectric (EID) and magnetization (EIM) behaviors were systemically investigated for this 0–3-type structured multiferroic ME composite. Significant electric-field-induced effects were obtained with a high tunability and a large EIM coefficient, which the former has a value of K = 3.35% under the low dc electric-field of 2 kV/cm and the later is in excess of 2.15 × 10⁻¹⁰ s/m at a low frequency of 1.0 kHz with a low magnetic bias field of 2000 Oe for this composite. It is also proved that its EIM behavior is strongly dependent on the bias magnetic field H _Bias and the frequency of driving electric-field. The measured EIM has an excellent linear relationship with the applied ac electric-field with amplitude varying from 7.1 to 73.6 V/cm. The electric-field-induced effects indicate that the 0–3-type particulate ME composites not only have physical interest but also have potential practical use.     

Plasma parameters of an electron cyclotron resonance discharge in a magnetic mirror in a quasi-gasdynamic confinement regime

An experimental investigation is made of x-ray bremsstrahlung in the 2–10 keV range of a pulsed discharge under electron cyclotron resonance conditions in a straight magnetic mirror system pumped by a high-power millimeter radiation beam. The plasma temperature and density were determined from the spectrum and intensity of the x-rays. The results indicate that a quasi-gasdynamic plasma confinement regime is achieved. Pis’ma Zh. Tekh. Fiz. 25, 90–93 (July 26, 1999)     

Influence of the concentration of a dispersed phase and of the magnetic field on the attenuation of ultrasonic waves in magnetic fluids

The regularities of the propagation of elastic waves of ultrasonic range in magnetic fluids have been experimentally established. The influence of relaxation processes — nonlocal heat exchange and viscous dissipation — on the coefficient of attenuation of sound has been revealed and a comparison to the existing theoretical data has been made. The dependences (anisotropic in form) of the attenuation of the wave’s amplitude on the value and direction of the magnetic field have been determined and an interpretation of the results obtained has been proposed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 5, pp. 133–140, September–October, 2007.     

Equilibrium states of an ion-beam plasma with magnetized electrons at low pressures

Results are presented of an experimental investigation of an ion-beam plasma with magnetized electrons in the cathode channel of an ion accelerator with an anode layer. New data are reported on the spatial distributions of the local plasma parameters (plasma potential, electron temperature, electron and ion densities) as functions of the external parameters of the discharge (magnetic field strength, anode voltage, and working gas pressure) in regions with strong, nonuniform electric and magnetic fields. Pis’ma Zh. Tekh. Fiz. 24, 33–38 (March 12, 1998)     

Reduction of aluminum oxide in a nonequilibrium hydrogen plasma

A new method is proposed and experimental investigations are carried out aimed at reducing aluminum oxide in a nonequilibrium hydrogen plasma of a combined glow discharge (CGD) at a pressure of 1315.8–13,158 Pa, a discharge current of 5·10⁻²–3 A, and a hydrogen flow rate of 10⁻⁶–10⁻⁴ nm³/sec. A high degree of conversion of the aluminum oxide (60%) with an energy consumption of 20 kW·h/kg of Al₂O₃ is attained. Reduction of metals from oxides and other compounds in a CGD nonequilibrium hydrogen plasma can be used for producing rare-earth and high-purity metals. Translated from Inzhenerno-Fizcheskii Zhurnal, Vol. 73, No. 3, pp. 580–584, May–June, 2000.     

Evidence for the Edge Magnetoplasmon “Acoustic” Mode in an Electron Layer over Liquid Helium

The spectrum of new modes of edge magnetoplasmons (EMP) in an electron layer over liquid helium was studied. The experiments were carried out in the temperature range 0.5–0.7 K at frequencies 0.87–1 MHz and electron density (1.5–3.5)·10¹²m⁻² in a magnetic field up to 0.5 T. Besides conventional edge magnetoplasmons and the EMP mode connected with the displacement of the electron sheet boundary, a new “acoustic” edge magnetoplasmon mode was observed in an electron layer over liquid helium for the first time. Spectrum of all three types of the magnetoplasmon modes are compared with the existing theories.     

Formation of magnetic fields inside massive conducting cylinders

The penetration of strong magnetic fields into a cylindrical vacuum space with massive metal walls has been experimentally investigated. A practical solution on acceleration of the penetration of the magnetic field into the working space has been proposed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 3, pp. 177–180, May–June, 2007.     

Dynamic characteristics of hydraulic brake devices with magnetorheological control

Consideration is given to the magnetorheological principle of control of an electrohydraulic brake device. The level of dissipation losses in the channel of the control unit, which determines the braking force in such systems, is regulated by a magnetic field adjusting a magnetosensitive pressure fluid to a prescribed effective viscosity. In an experiment, control of the main parameters characterizing the force and frequency characteristics of the device has been accomplished. It is found that the characteristic time of developing a braking force is 10⁻³ sec, and the speed of response of the system is mainly limited by the frequency characteristics of the inductor of the magnetic field of the magnetorheological throttling valve. Academic Scientific Complex “A. V. Luikov Heat and Mass Transfer Institute,” National Academy of Sciences of Belarus, Minsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 72, No. 5, pp. 874–880, September–October, 1999.