Microfocus X-ray Tubes

Introduction. X-ray inspection plays a unique role among all nondestructive testing methods for products and materials due to sufficiently high resolution and high penetrability. The present study is designed to consider the key features of microfocus X-ray sources, their areas of application, and main technical characteristics.Aim. The paper aims to systematize information and review modern X-ray radiation sources for the implementation of microfocus radiography.Materials and methods. The main designs of microfocus X-ray tubes (soldered and demountable) were considered relying on the experience of the St Petersburg State Electrotechnical University in developing and operating such equipment, as well as the experience and open-access publications of foreign researchers and developers. Data collected by leading research teams over the last ten years were analyzed.Results. The paper presents design features for each main type of microfocus X-ray tubes – soldered and demountable. All key structural elements are considered: an anode assembly, a cathode assembly, and a focusing system. The influence of anode target material on the X-ray tube radiation spectrum is shown. An original design of a liquid-anode microfocus X-ray tube is described to demonstrate its key features and advantages. In addition, the paper gives an overview of cathodes used in microfocus X-ray tubes (tungsten cathode and lanthanum hexaboride cathode), as well as providing a detailed description of calculations performed for focusing systems. Finally, the designs of modern X-ray tubes are presented.Conclusion. Modern X-ray tubes are high-tech products that allow for high-resolution research of various objects. The main advantage of testing performed with the use of X-ray tubes consists in high resolution (micron and submicron). The X-ray images of test objects used to determine their spatial resolution are given, which clearly illustrate the vast possibilities of this technology. In addition, ways to improve microfocus X-ray tubes are briefly discussed. The considered materials can be useful in selecting a nondestructive testing tool, as well as in developing and creating X-ray systems on the basis of microfocus X-ray tubes.

Investigation of the thermal state of the elements of a technological electron beam gun under long–term operating conditions

The paper presents the results of a study of the thermal state of the elements of the cathode assembly of the ELA–15 welding electron gun. It was revealed that in short–term operating modes of the gun (up to 60 minutes) at any energy parameters of heating the hexaboride cathode, it is possible not to use forced cooling of the cathode assembly. The case temperature in such modes did not exceed 30°C. The increase in the temperature of the gun body occurred 15 minutes after the start of heating the cathode. In long–term operating modes with forced cooling of the gun, the temperature of the gun body increased by 2 – 3°C and remained stable throughout the operation. When the cooling was turned off, the temperature of the gun body reached a critical value in 60 minutes. The section of natural cooling of the cathode obtained in the work, which appears when the heating of the cathode is stopped, is well approximated by a power function. It is convenient to use this dependence to verify the mathematical model of the thermal state of the electron gun.

Токовые характеристики сильноточной электронной пушки с многоканальным инициированием взрывной эмиссии пробоем по поверхности диэлектрика

Current characteristics of a plasma-filled, high-current electron gun with a new cathode assembly which can be named as a controlled explosive-emission cathode have been investigated. Multi-gap initiation of explosive emission is performed with the use of parallel operated, resistively decoupled arc plasma sources which electrodes and tube ceramic isolators are built-in to the explosive-emission cathode. The initiation of explosive emission was performed using 69 operating in parallel arc plasma sources whose electrodes and tubular ceramic insulators are inserted to the disk explosive-emission cathode. Experiments have demonstrated operability of high-current electron gun with a new cathode assembly at accelerating voltage up to 30 kV and its good emissivity (average in area current density) which was approximately 1.4–2.4 times higher than an emissivity of traditional electron gun with plasma anode and multi-wire copper cathode.

The possibilities of using a femtosecond fiber laser in the manufacture of thermionic cathodes

The possibilities of using a fiber laser with a femtosecond duration of radiation pulses in the manufacture of miniature thermionic cathodes made of 50 μm of tungsten-rhenium foil are shown. The cathode assembly, consisting of a heater and a core, is made in the form of a solid structure with an oxidecoating applied by ion-plasma sputtering. The emission characteristics of the cathode are presented.

Катодный узел сильноточной электронной пушки с многоканальным инициированием эмиссии пробоем по поверхности диэлектрика

A new scheme of the cathode assembly of a high-current electron gun is presented. Initiation of explosive emission is performed with the help of sixty nine simultaneously operating spark gaps which electrodes and tube ceramic isolators are inserted into a disc explosive-emission cathode. The operability and high emissivity of the cathode assembly which exceeds by 1.5‒1.7 times the value inherent in traditional scheme of an electron gun with plasma anode and copper-braid explosive-emission cathode has been demonstrated.

Перспективы использования рентгеновских трубок с автоэмиссионным катодом и "прострельным" анодом в диапазоне мягкого рентгеновского излучения

The use of field emission cathodes in the design of x-ray tubes requires the placement of a cathode assembly with a small distance from the anode, complicating the output of radiation. Most acute this problem occurs when generating a relatively soft spectrum with wavelengths of 1-10 nm: in this case, the accelerating voltage does not exceed several kilovolts, and the inter-electrode distance composes several hundred micrometers. In this work, we experimentally demonstrated the applicability of beryllium-based submicron films as “shot-through” anodes for generating the Be K line ( = 11.4 nm) and the associated bremsstrahlung spectrum. In particular, the characteristic radiation of a tube with a field emission blade cathode and a Be film anode was recorded within the scheme of a grazing incidence grating spectrometer. The characteristics of beryllium films necessary for the development of X-ray tubes of this type with a higher output power are determined.

Understanding the Effect of Electro-Oxidation Process Variables on Reactive Navy Blue Rx Dye Decolorization

The study investigated the study of electro-oxidation treatment on Reactive Navy Blue RX dye simulated wastewater using graphite and stainless steel electrode material as anode-cathode assembly. The effect of initial pH, electrolyte dose, applied current, dye concentration, and time, has been investigated. Preliminary test to understand influence of initial pH and NaCl dose on EO process has also been investigated and further work was carried at optimized initial pH 5 and NaCl dose 500 mg/L. From the experiments it was observed that with increase in current density the color removal also increases while with increase in initial dye concentration, removal efficiencies decreases