Filament Circuit Research Articles

Research of low frequency components of a magnetron oscillator spectrum

In this article the resonant properties of the plant for the investigation of Ku-band magnetrons’ operation in the low-frequency domain from 100 kHz to 35 MHz were experimentally investigated.Improving the electronic devices’ quality is an important task for Ukrainian scientists. It will increase the duration and reliability of sophisticated equipment based on electronic devices, as well as improve the production economic efficiency in the electronics industry.The most common M-type device, the magnetron, was selected as the studied object. Low-frequency oscillation modes were influenced to the magnetrons’ output spectrum quality. Theses modes can occur in the device itself, as well as in the power supply circuits or be induced from the ether. It is hypothesized that spurious oscillations which may impair the electronic devices output spectrum quality, in particular magnetrons, will be amplified at frequencies which the resonances in the device, the supply circuits, and the system as a whole are observed. The experimental study is aimed to determine the frequency domain of the possible occurrence of these spurious oscillations.The measuring plant for magnetron research consists of a magnetron, a wave type transducer, an absorbent power meter, and a spectrum analyzer. The total error of this setup does not exceed ±4 dB.The resonant properties study of this plant in the low-frequency domain was performed according to the classical scheme of the resonant properties study of oscillating circuits. The total relative error of resonance properties measurements did not exceed ±8 %.As a result of research, it was discovered a pronounced resonant peak of the magnetron supply circuits in the 30 MHz band, magnetron filament circuits have a pronounced resonant peak in the 20 MHz band, the magnetron has two pronounced peaks in the 5 and 20 MHz band and two peaks in the 15 and 35 MHz band, the system as a whole has two pronounced peaks in the 10 and 30 MHz band.

Integrating Flexible Filament Circuits for E‐Textile Applications

AbstractPractical wearable e‐textiles must be durable and retain, as far as possible, the textile properties such as drape, feel, lightweight, breathability, and washability that make fabrics suitable for clothing. Early e‐textile garments were realized by inserting standard portable electronic devices into bespoke pockets and arranging interconnects and cabling across the garment. In these examples, the textile merely served as a vehicle to house the electronics and had no inherent electronic functionality. A reduction in electronic component size, the development of flexible circuits, and the ability to weave robust interconnects offer the potential for improved levels of electronic integration within the textile. The weaving of electronic circuit filaments less than 2 mm wide into fabrics such that the electronics are fully concealed in the textile and given extra protection by the surrounding textile fibers is introduced. The failure mechanisms for different filament circuit designs before and after integration into the textile are investigated with a 90° cyclical bending test. Results show that encapsulated filament circuits embedded within the textile survive 45 washing cycles and more than 1500 cycles of 90° bending around a bending radius of 10 mm, performing five times better than equivalent filament circuits before integration into the fabric.

Use of logarithmic sensitivity in power system analysis: the example of lighting circuits (hot filament, LED and fluorescent lamp circuits)

Logarithmic sensitivity characteristics were widely employed by Ch. P. Steinmetz in his classical studies of magnetic systems. In the present case, the authors deal with power sensitivity, K(U) = (dP/P)/(dU/U), where U is the amplitude (scaling factor) of the applied voltage and P is the averaged power. That such characterisation can be suitable for non-linear power systems is demonstrated for lighting systems: incandescent lamp circuits (i.e. the hot filament), LEDs and fluorescent lamp (FL) circuits. For FL circuits, the problem of minimisation of K(U) is shown to be practically and methodologically very important. On the pedagogical regard, the opinion is expressed that the described use of K(U) should be taught in basic courses of circuit theory and power systems.

SN-series Pseudospark Switches, Operating Completely without Permanent Heating. New Prospects of Application in Pulsed Power

Since 1990th a process of exclusion of gas-discharge and vacuum devices (GDDs and VDs) from Pulsed Power systems has been conditioned by two major factors – unsufficient service time and necessaty to supply filament circuits of GDDs and VDs. And the process was inspite of a number of positive features of GDDs. In the report a design and longterm test results of TDI-type pseudospark switches (PSSs) are presented. The PSSs are a great extent free of the mentioned shortcomings, in particular, the devices are capable of operating without filament, providing a wide number of perspective applications of the tubes in Pulsed Power

Thermodynamic Steady States in Simple Electrical Circuits

Electrical circuits provide good examples of systems which gravitate towards the three possible thermodynamic conditions of equilibrium, metastability or dissipative steady state. Circuits are driven towards any one of the three conditions simply by increasing total entropy or decreasing available energy. The thermodynamic condition for steady state conduction in a number of simple LCR and hot filament circuits is found to be 1/( ds tot / dψ ) = 0 or 1/( de avail / dψ ) = 0 where s tot and e avail are the total entropy and available energy of the system and its surroundings, and ψ is any single valued variable which describes the condition or state of the total system. This is the inverse of the equilibrium and metastable conditions. It holds for all systems examined, whereas the Onsager-Prigogine principle, ds tot / dt = 0 at steady state, holds only in one case. This shows that the principle is not the causative principle of the steady state. As expected, the analysis also demonstrates that electric circuit theory is fully consistent with the second law of thermodynamics as well as with the first.

The Solar Origin of the 6 January 1997 Coronal Mass Ejection

By using observations from the satellites of the International Solar Terrestrial Physics (ISTP) Observatories, the relationships among the coronal mass ejection (CME), the helmet streamer and the disappearing filament (DSF) have been studied. Our main conclusions are as follows: (1) The DSF disrupted the streamer, thus resulting in the restructuring of coronal field and causing the mass in the helmet streamer to form the CME. (2) The DSF under a helmet streamer and the sigmoid soft X-ray loop are possibly the precursors of the 6 January 1997 CME. (3) The energy stored in the filament circuit and the energy of the CME (include kinetic, potential and magnetic energies) are estimated and it is found that there was enough energy stored in the filament to provide the CME of 6 January 1997. (4) The CME's speed in response to the DSF is calculated. It is showed that the DSF can drive the CME to the observed speed.

Electron emission stabiliser with double negative feedback loop

The addition of another loop in a typical DC electron emission controller between (a) the filament supply point and (b) the inverting input of the operational amplifier improves the work of the whole system. If this loop consists of a diode directed from point a to point b and a capacitor connected in parallel to the diode the system has the following new features: (1) it enables a gradual heating of the filament for its outgassing when the system is turned on, (2) the filament is protected in the case when the main feedback loop having external parts is accidentally broken, (3) the capacitor eliminates the generation of any AC current in the filament circuit. The last property notably extends the lifetime of the filaments working in a strong magnetic field, e.g. in mass spectrometers.

Thermal Conduction Measurements of Materials using Microwave Energy

ABSTRACTWe have developed a new technique to measure the thermal conductivity of materials using microwave energy. A thermal wave is induced in a material of unknown thermal conductivity using a pulse of microwave energy. This energy is incident on one side of the material. The corresponding temperature rise of the opposite side of the material is measured. The thermal diffusivity of the material can then be determined in the same way as ‘laser flash’[1]. Some of the advantages of the microwave system are the relatively low cost of the magnetron compared to the high energy laser, easily variable pulse length, and accurate measurement of the reflected energy.The microwave system consists of a 2.45 GHz magnetron that is pulse modulated to energies as high as 10 J. A typical pulse lasts for 1 ms with rise and fall times of 10µs. This is achieved by a high voltage source (5 – 8 kV at 1 – 2 A), switched by a high power, rf transmitting tube connected in the filament circuit of the magnetron.

Preflare energy build-up in a filament circuit

The two-dimensional Van Tend and Kuperus (1978) scenario for pre-flare energy build-up is extended to a fully three-dimensional model and applied to the 16 May, 1981 flare observed at Debrecen. It is shown that there is plenty of free energy (1033 erg) available to explain the ensuing large two-ribbon flare. This estimate is an order of magnitude larger than the simple estimate made by Van Tend, as a result of the three-dimensional character of the present model. It is further confirmed that the global form of the preflare circuit is decisive for determining the amount of energy stored in the preflare configuration, while the internal structure of the filament is of little importance. This is in accordance with the similar claims of Alfven and Van Tend and Kuperus. Order of magnitude estimates are derived for all the lumped circuit parameters of the preflare filament-return current circuit; self-inductance, resistance, current strength, and applied voltage. It is found that the model gives correct predictions for the independently observed photospheric flow velocity and current strength in filaments.

Emission current regulator for ion cyclotron resonance spectrometers using an optical coupler

An electron emission current regulator for an ion cyclotron resonance spectrometer which operates well in the pulsed grid modulation mode for frequencies above 30 Hz was constructed. It regulates the filament current by comparing the feed-back signal of the electron emission current with a reference voltage. The feed-back signal is transmitted through an optical coupler from the emission current detector to the filament circuit since the common voltages of these circuits are different. It regulates the emission current in the range from 10 −6 to 10 −9 A maintaining a stability of 0.2% h −1.

Design of Filament Current-Surge Restricting Devices for High-Power Electronic Tubes

The switching-on current surge of the high-power electronic tube filaments may be restricted by gradually applying the filament voltage, series connecting resistors or an inductor in the filament circuit, and by using a leaky-flux filament transformer.

Quadrature Operation of Filamentary Thermionic Gas Tubes

Filamentary thermionic gas tubes, when operating with the anode and filament voltage inphase, exhibit a marked temperature gradient along the filament. When the magnitude of the anode and filament currents are of comparable value, the resulting nonuniformity in filament temperature may be sufficient to cause short tube life and unreliable operation. This condition is not corrected appreciably by any special arrangement of anode current return connection to the filament circuit. By operating the tube with the anode and filament voltages in quadrature, <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> approximately double the value of current permissible under the inphase operating condition may be conducted before the same temperature difference results.

The Direct-Current Amplifier in Industry

IN a paper read before the Institution of Electrical Engineers on March 6, D. C. Gall describes the design and behaviour of a direct-current amplifier, entirely alternating-current mains-operated, and having an accuracy independent of mains' fluctuations or change in valve characteristics. The voltage to be amplified is applied to a reflecting galvanometer in series with a resistance. The light from the galvanometer strikes a photocell which controls the grid voltage of a thyratron valve, this voltage shifting according to the illumination of the photocell. The grid voltage makes the thyratron conducting between its anode and filament circuit for part of the positive half-wave and, as the phase of the grid voltage advances, the conducting period lengthens, giving a larger effective rectifier current output. This current is fed back through the resistance so that the voltage drop opposes the applied voltage, the drop rising until the input voltage is balanced. Output current is thus proportional to input voltage. The thyratron anode current is supplied from a 250v. section of the mains transformer and it operates the amplifier output circuit apparatus. Smoothing condensers and inductances convert the thyratron unidirectional current pulses into steady direct current and suppressing circuits eliminate radio interference from these pulses. The amplifier has an output of three watts and a power gain of about 1010. It can be used as a voltage or current-amplifier and is extremely stable. It has been applied to high-speed temperature-recording of liquid steel, to the metering of heat transport in large hot-water plants, to optical pyrometry, measurements of illumination by barrier-layer type photo-cells, to the polarograph and to many other problems in which very small E. M. F.'S are available as a function of the quantity to be measured. The departure from linearity of response is of the order of only a few parts in 10,000, and voltages of a few microvolts and currents as low as 0.01 microamp. can be amplified and thus used to operate recorders and controllers.

A Static Constant-Current Circuit

Static constant-current circuits have been constructed by connecting an iron-core reactor, with predetermined characteristics, in parallel with a capacitor of a specified size such that the resultant input current is independent of line voltage. This parallel circuit is connected in series with the element through which the current is to be regulated. The current will remain essentially constant for large variations in line voltage; large variations in load impedance; or a variation in both quantities simultaneously as long as the variation in voltage across the parallel circuit does not exceed certain limits. This type of circuit is useful for applications where a constant heating independent of line voltage is desired; for series lighting circuits; and vacuum-tube filament circuits.

The Harmonic Mode of Oscillation in Barkhausen-Kurz Tubes

The phenomenon of harmonic operation of Barkhausen-Kurz tubes employing a resonating helical grid is investigated by the use of tubes with the plate cut transversely into three sections. It is shown that the fundamental or Barkhausen frequency may be elicited by exciting the grid at its central portion, but that if the grid is excited at its ends either symmetrically or unsymmetrically the oscillations occur at double the Barkhausen frequency. This doubled frequency is that usually generated by tubes of this type. It is also shown that it is essential to tune the filament circuit of the oscillator if maximum power output is desired.

Development of a System of Line Power for Radio

A short history of the development of power supply apparatus for radio receivers is given, including a brief discussion of the technical requirements, such as the most desirable suppression characteristics, the necessity for voltage regulation, etc. The various devices which have been developed are described. The present status of the art and the scope and limitations of the different types of apparatus are discussed. The series wired radio set with common power supply for plate filament and grid circuit is discussed in some detail, and curves of the operating characteristics of such a set are given.

The valve filament at constant voltage

When the filament of a thermionic valve emits and a thermionic current flows from the filament to the anode and through an external circuit back to the filament, the filament current is necessarily different at all points along the filament. An ammeter in each filament lead and a voltmeter across them will all read differently when the valve emits, the actual deviations depending on the electronic emission and the circuit used. The only exceptions are the case of a filament connected directly to a source of P.D. with no intermediate rheostat, when the voltage will be maintained constant by the supply, but the currents will vary in any case. The other exception is that of the valve with the separately heated cathode, the potential of which is uniform. The variations of the reading of the filament voltmeter and ammeters have been investigated experimentally, and a circuit has been devised in which there is no change of reading of the voltmeter or either ammeter when the anode current is switched on and off. The current read is the filament battery current, and with this circuit tests may be repeated on valves with the certainty of the filament conditions being constant for different tests. An investigation was also made of the validity of the practice of readjusting the filament voltage after switching on the anode potential, and it was found that this practice is not correct as regards maintaining the filament under constant conditions, except for those valves intended to be run without a rheostat. All tests were made with valves used as diodes, as in this case the emission is usually greater than the anode current when the valve is used as a triode. For standard tests on valves used as triodes the precautions necessary to maintain constant filament conditions are of less importance. For standard valve tests the circuit devised should be adhered to, and the practical means of ensuring constant conditions are indicated. The method of reducing the asymmetry of the temperature gradient of large valves used as rectifiers is of some interest here, and the conditions have been calculated. The experimental work necessary shows how fine precision measurements may be made with commercial instruments, as numerous checks are possible, most of which show up the accuracy of the majority of the readings, which in most cases involved a change of less than one scale division. Finally, a valve was tested with its filament supplied with A.C., and various circuits tried. It was found immaterial to which point of the filament circuit the anode return was connected, on account of the symmetry of the temperature gradient, at any rate at 50 similar and above.

On the Investigation of the Latest Electric Lamps, Radiation Photometer and Radio Tube

In the precent paper the author describes the investigations carried out in his laboratory as the following:I.Incandescent arc lampThe ordinary tungsten arc lamp hitherto introduced in the market can not be dis pensed with the complicated starting device.The tungsten incandescent arc lamp here described was invented by the anther with C.Matsuda, and is to be considered as the combination of the low pressure gasfilled in candescent filament lamp and the tungsten arc lamp.Incandescent filament serves not only as the ordinary incandescent lamp filament, but also as the ioniser of the gas between the tungsten electrodes.Steadifying resistance for the arc is inserted in series or parallel to the filament circuit according to the case may be. Thus in this lamp starting device is not necessary, contrary to the ordinary tungsten arc lamp, and when the lamp is switched on the supply mains, arc is started between the tungsten electrodes just as simply and easily as the ordinary incandescent lamp.Special protecting tungsten shields are provided to the terminals of the lead wires to protect against the bombardment of the ionised gas upon the incandescent filament.II.Low pressure gas-filled lampThe principal purpose of the ordinary gas-filled lamp is to reduce the evaporation from the incandescent tungsten filament, so that the lamp can be opered at much higher temperature than the ordinary vacuum incandescent lamp.But the convection loss is hereby introduced due to the filling gas, and it amounts to a comparatively high value. Low pressure gasfilled lamp is thus preferable if the corona discharge can be prevented by some simple means.To overcome this difficulty and provent the corona discharge, a small conducting wire net or mica plate shield is introduced in the path of the ionised ions between the filament terminals.Thus the net or plate acts as the electrical and mechanical shield protecting against corona discharge and against the bombardment of ions.III. Semivacuum lamp.Another low pressure gasfilled lamp, called “Semivacuum lamp” or “Economy lamp”, having a special protecting device against the corona discharge was invented at the Aoyagi Lobaratory.Nitrogen gas being filled at the pressure less than about 50m.m. of mercury.The nitrogen gas in the bulb is not introduced externally, but produced by the decomposition of a chemical, azide of alkaline earth metals, sealed in the bulb. The laboratory test for this lamp gives the better results compared with the ordinary gasfilled lamp, and its production cost may be reduced compared with the latter.IV. A new radiation photometer.The Aoyagi laboratory invented a new photometer to measure radiation, making use of the resistance variation of the two tungsten filaments sealed in the vacuum tube, due to the exposure of the radiant energy under consideration. The above two filaments form the two opposite arms of a Wheatstone bridge. The main advantages of the instrument are that it has great sensibility and no effect of room temperature.It is convenient to measure and to describe easily the light distribution curve, Rousseau curve, etc. by means of a given simple mechanism.V. A new radio tubeA new radio tube was invented at the Aoyagi laboratory, which gives a large electron current notwithstanding the small filament current and low filament temperature. The tube contains the vapour of zinc, cadmium or both which increases the activation of the filament.The production cost is much reduced by using the zinc plate or alike instead of the nickel plate.