Ignitron

Abstract: Industrial electronics is the phrase usually employed to cover the use of vacuum tubes in fields outside of communication. The term was originally applied to the Tungar Rectifier (about 1915) and the use of phototubes (about 1927). By 1930 Industrial Electronics became a growing business. However, its early growth was slow, because there was a general mistrust about the dependability of tubes. Wider use of thyratrons that could handle currents in amperes was an important contribution; the development of ignitron tubes, and the use of steel envelopes for them, were considerable factors; also, such new applications as high frequency for induction and dielectric heating helped in the advancement.

Abstract: Previous work in the field of inductive energy storage and control is described. The need for a fast, reliable switch for the control of such systems is pointed out. A new inductive energy storage switching system that fulfills this need is described. The new system utilizes an ignitron bridge circuit and a capacitor to invert from the unidirectional current of an inductive source to an alternating voltage of triangular waveform. The alternating voltage is used to charge and periodically recharge a small capacitor. This capacitor in its turn supplies energy to the load. Thus, by the use of two capacitors, whose maximum stored energy is very small compared to the total energy to be transferred, the stored energy may be transferred to the load in discrete parcels. The disassociation of storage and load circuit allows the transfer of all stored energy to the load, with the exception of the usual resistive energy loss imparted by circuit elements, a quantity that can be kept small. Therefore, the energy efficiency is higher than heretofore attained by inductive energy storage systems. The above-described switching system does not depend upon moving contacts or mechanical devices. The system results in significant reductions in initial cost per joule of energy stored as compared to the cost of capacitive energy storage systems. The inherent low energy efficiency of earlier inductive energy storage systems is discussed and it is pointed out that the theoretical energy efficiency of the bridge scheme is much higher.

Abstract: An adjustable waveform excitation source for exploding thin film atomic spectroscopy is described. Waveform control is achieved through a saturable inductor having control windings and placed in series with the underdamped discharge tank circuit. This results in a high-current pulse for efficient sample atomization followed by a low-current measurement interval. When this is combined with gated integration, ∼15-fold increases in analysis line/background intensity ratios are observed for V and Mn. With additional inductance added to the circuit, the current and duration of both the atomization pulse and measurement interval can be adjusted independently. Other features of the excitation source include a plasma shunt capacitor, which results in more reproducible dielectric breakdown of the plasma support gas, and a variety of high-current series switches for initiating the discharge. Triggered spark gap, gravity operated spark gap, silicon-controlled rectifier, and ignitron switches are compared with respect to resistance and switching time jitter. Examples of discharge current and voltage waveforms and preliminary analytical data are presented.

Abstract: The construction and the characteristics of recent high- speed soft x-ray generators designed by the authors are described. The flash x-ray generators having cold-cathode radiation tubes are three types as follows: (1) soft generator utilizing an ignitron, (2) plasma generator for producing high-intensity characteristic x rays, and (3) water-window generator having a high-durability fermite capillary. In general, when we employed the flash x-ray generators with diodes, the pulse widths had values of less than 200 ns. Next, the x-ray duration was almost equivalent to the durations of the tube voltage and current during their damped oscillations when the water-window generator was employed. The maximum tube voltage was increased up to 100 kV, and the tube currents achieved with high-intensity generators were more than 10 kA. In order to obtain kilohertz-range repetition rates, we have developed two types of stroboscopic x-ray generators having hot-cathode tubes as follows: (4) low-photon-energy generator utilizing and triode and (5) high-photon-energy generator with a diode. As the duration was controlled in a microsecond range by using the low-photon-energy generator, sufficient x-ray intensifier for the normal radiography were obtained. The maximum photon energy could be increased up to about 200 keV by the high-photon-energy generator having a double transformer. Using these generation, we performed high-speed soft radiography.