nomagicpill

Vacuum: Theory and Technologies This post can be described as a general summary of John O'Hanlon's A User's Guide to Vacuum Technology (Goodreads, Amazon) without most of the math and models used. Some sections are completely skipped over: pump fluids, materials in vacuum, lubrication. O'Hanlon's book is a comprehensive resource on vacuum technology, especially as related to semiconductor processing. Other resources are used where O'Hanlon's textbook is lacking in quality or mention, i.e., it is not discussed in the book. Contents * What is Pressure? * Gas Flow * What is Vacuum? * Vacuum Measurement * Outgassing * Flow (In and Out) * Low Vacuum Pumps * High Vacuum Pumps * Connections (Joints) and Valves * Leak Detection * Residual Gas Analysis * Vacuum Systems * See Also What is Pressure? Pressure is defined by the simple equation: P=FA where P is pressure, F is force, and A is the area the force is exerted on. A common experiment to show this equation in-action is laying on a bed of nails: if F (the person's body) stays constant and A (the area of the bed) is large, the pressure exerted on the skin will be minimized, preventing penetration. But if it's a single nail... The ultimate torture devi... wait, this doesn't hurt! (source) Now that pressure has been shown with an actual body (literally!) of mass, what about pressure that is invisible, e.g., air? From the Maxwell-Boltzmann distribution, which is used to find the distribution of the speeds of particles within an ideal gas, the N2 molecule at a temperature of 0 °C moves at a probable speed of: vp,N2=√2kBTmN2=400m/s where kB is the Boltzmann constant, T is temperature, and m is the particle's mass. The root-mean-squared speed is found by: vrms,N2=√3kBTmN2=500m/s Quite fast! If a human got hit by a car going the same speed (900 mph, 1500 kph), they would surely die. The difference is the size of th