JR Macdonald Laboratory 1998 Summer Short Course:

	Introduction to Vacuum Physics and Technology:	
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      Problem 3a) A differentially pumped gas target has 0.1"
	diameter beam entrance- and exit apertures. It is mounted in
	the center of a 4" 4-way cross (4x3.75" long). The
	differential pumping is accomplished with a TPU400
	turbomolecular pump (6" inlet port). The TPU400 is adapted
	to 4" with a zero-length reducer and connected with a 7.5"
	long, 4" diameter nipple to the 4 way cross. What is the
	expected pressure in the differential pumping region if the
	gas target is kept at 0.1 Torr Hydrogen ? 



      Problem 3b) What is the expected pressure in the
	differential pumping region if the gas target is operated
	with 0.1 Torr Nitrogen? 


      Problem 3c) What is the expected Nitrogen pressure in the
	differential pumping region if we eliminate the 7.5" long 4"
	diameter nipple?