startup. The Zener diodes 124A, 124B (collectively referred to as 124) allow the respective neutralizer cathodes to float at whatever potential is necessary to supply the correct electron emission to neutralize the positive ion beam of thrusters 104.
One critical element of an ion thruster is the neutralizer cathode. The neutralizer cathode, commonly a hollow cathode, is generally life limited by its operating temperature; the higher the operating temperature, the shorter the operating life of the cathode (and accordingly, the shorter the operating life of the thruster). Because the operating temperatures of such cathodes are directly proportional to their emission current, control of the emission current in the neutralizer cathode is important to maximizing the thruster's operating life. Consequently, in order to maximize operating life, a single PPU is[Automatic feeding systems for horses in group housing systems with regard to animal welfare. Part 2: Comparison of different automatic feeding systems].
Comparison with regard to animal welfare of different automatic feeding systems for hay and concentrate in group housing systems for horses using parameters of ethology and physiology. Parameters of research comprised: duration of stay, frequency of visit, threatening behaviour with and without risk of injury, and avoiding behaviour as well as heart rate and injuries of the integument. 452 horses were observed at the feeding area of 32 run-out-sheds. Every group of horses was continuously observed following the pie chart system for 24 hours. The "walk-through" station significantly reduced the number of conflicts in the feeding area, whereas those systems which are appropriate for the feeding horses