Glow cathodes

A conclusion has been drawn based on the results of the studies that a most convenient source of RGMAs suitable for sensor measurements is represented by discharge sources of the diode type, sources that operate in the d.c. discharge, glowing cathode mode. 

The current density jj s for this process, which at high temperatures is also called glow emission, was originally calculated by Richardson for glow cathodes in vacuum valves and, taking the Schottky effect into account, is given by ... 

Microwave plasmas are operated at 1-5 GHz. They are produced in a magnetron. The electrons emitted by a glowing cathode are led through a cavity with a series of radially arranged resonance chambers to which an ultra-HF (UHF) field is applied. 

Hydrazine is prepared, anhydrous and in good yield, by glow discharge electrolysis of liquid ammonia a platinum cathode is immersed in liquid and a platinum wire anode is mounted just... 

Gas used Cathode glow Negative glow Positive glow... 

In process A, slow electrons are accelerated until they have sufficient energy to again excite gas atoms this is the start of the negative glow, just like the process in the cathode glow (Figure 6.4). 

If the electrodes are moved closer together, the positive column begins to shorten as it moves through the Faraday dark space because the ions and electrons within it have a shorter distance through which to diffuse. Near the cathode, however, the electric-field gradient becomes steeper and electrons from the cathode are accelerated more quickly. Thus atom excitation through collision with electrons occurs nearer and nearer to the cathode, and the cathode glow moves down toward the electrode. 

Irradiation of the cathode by the glow that starts (photoelectric release of electrons)... 

Use of glow-discharge and the related, but geometrically distinct, hoUow-cathode sources involves plasma-induced sputtering and excitation (93). Such sources are commonly employed as sources of resonance-line emission in atomic absorption spectroscopy. The analyte is vaporized in a flame at 2000—3400 K. Absorption of the plasma source light in the flame indicates the presence and amount of specific elements (86). 

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