Feedthroughs, vacuum

Collar, feedthrough (vacuum technology) A short metal cylinder on which feedthroughs are mounted and located between the baseplate and the bell jar. Provides a sealing surface for both the baseplate and the bell jar. 

Figure 1. Schematic Diagram of the off-axis radiant heated reactor. A. cell body B. linear/rotary motion feedthrough C. transport rod D. projector bulb E. reflector F. insulated stainless steel enclosure G. air cooling port H. gas inlet I. gas outlet/pumping port J. chromel/alumel thermocouple K. high vacuum gate valve L, sample mount.

Figure 4.2 The micro-Flow Tube Reaetor/Mass Spectrometer instrument. 1 — heated gas inlet/vacuum feedthrough, 2 — hot zone of flow tube, 3 — multiion source block, 4 — ion guide, 5 — quadrupole mass spectrometer, 6 — ion guides, 7 — reaction cell, 8 — quadrupole mass spectrometer, 9 — daly detector... 

Example A vacuum chamber of 500 I may have a total surface area (including all systems) of about 5 m. A steady gas evolution of 2 10 mbar l/s is assumed per m of surface area. This is a level which is to be expected when valves or rotary feedthroughs, for example are connected to the vacuum chamber. In order to maintain in the system a pressure of 1 10 mbar, the pump must have a pumping speed of... 

The setup used in these experiments is remarkably simple all that is required is a mechanical vacuum-feedthrough by which a rotatable rod, made of or topped by the desired material, can be introduced. Pulses of the fundamental of a Q-swiched, pulsed Nd Yag laser (typically 20-80 mJ/pulse, 1-10 Hz) are focused on that target, either through a separate port, or simply from behind the cold window.In order to avoid formation of pits that lead to a greater propensity for cluster formation, the rod is rotated slowly such as to expose a fresh surface to successive laser pulses. ... 

Make sure that the mold surface and all gates and feedthroughs are vacuum tight. 

The third example of field emission from Si-based nanowires is from the aligned SiC nanowires. The field emission measurements [68] were carried out in a vacuum chamber at a pressure of 5 x 10 Torr at room temperature. An oriented SiC nanowire array, which was used as the cathode, was stuck to a stainless steel substrate by silver paste with the bottom end of the nanowires facing upward. A copper plate with a diameter of 1 cm, mounted on a precision linear feedthrough, was used as the anode. Field emission current densities of 10 pA cm were observed at applied fields of 0.7-1.5 V pm and current densities of 10 mA cm were realized at applied fields as low as 2.5-3.5 V pm , as shown in Figure 10.35. These results represent one of the lowest fields ever reported for any field-emitting materials at technologically useful current densities. We attributed this emission... 

An important feature of all these devices is that one or more vacuum feedthroughs are required for linear or rotary motion. A common problem with such feedthroughs is that small amounts of sorbed gases... 

Machinable glass-ceramics are based on internally nucleated fluoromica crystals in glass (Beall 1971a). One commercial material has been marketed for 20 years under the trademark MACOR and has found wide application in such diverse and speciality areas as precision electrical insulators, vacuum feedthroughs, windows for microwave-type parts, samples holders for field-ion microscopes, seismograph bobbins, gamma-ray telescope frames, and... 

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