Vacuum systems for storage rings

Synchrotron light sources are electron storage rings that produce synchrotron radiation by accelerating electrons in a circular storage ring. The synchrotron light (photon beam) is then used to irradiate various sample materials for basic and applied research in such fields as solid state physics, biology, chemistry, surface science, and technology.The electron storage ring must provide an ultrahigh vacuum environment for the electron beam to minimize electron residual gas collision which would shorten the beam-lifetime. This article will discuss the design of electron storage ring vacuum systems and materials, and how the choice of materials can affect the machine design.A typical electron storage ring is shown in Figure 1. It consists of an injector (linac and booster), transport system, storage rings, and experimental photon beam lines. These machines vary in size from a few meters in circumference for a compact light source used for x-ray lithography, to a few hundred meters in circumference for high energy physics.The vacuum system for an electron storage ring is an all-metal ultrahigh vacuum system. The operating pressure is in the low 10−9 torr range with stored electron beam, and 10−10 torr without beam.Certain unique vacuum problems must be faced in electron storage ring design: photon-stimulated gas desorption, power dissipation in the chamber walls, impedance changes due to changes in the chamber cross section, conductance limitations, accurate placement of the chamber, and all of those sundry problems associated with a large bake-able all-metal UHV system. Some of these characteristics are illustrated schematically in Figure 2. Two excellent papers that address many of these issues have been written by N. Mistry (system design) and H. Wiedemen (impedances and instabilities).

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A SYSTEM FOR PROTECTING AN OIL DIFFUSION PUMP AGAINST FAILURE OF THE MECHANICAL FORE PUMP, COOLING WATER, OR ELECTRICITY

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068710 ◽

1970 ◽

Vol 28 ◽

pp. 344-345

Author(s):

W. C. Bigelow ◽

F. B. Drogosz ◽

S. Nitschke

Keyword(s):

High Vacuum ◽

Cooling Water ◽

Effective Protection ◽

Pump Line ◽

Diffusion Pump ◽

System Pressure ◽

Control Relay ◽

Vacuum Systems ◽

Vacuum Gage ◽

Pressure Switch

High vacuum systems with oil diffusion pumps usually have a pressure switch to protect against Insufficient cooling water; however, If left unattended for long periods of time, failure of the mechanical fore pump can occur with equally serious results. The device shown schematically in Fig. 1 has been found to give effective protection against both these failures, yet it is inexpensive and relatively simple to build and operate.With this system, pressure in the fore pump line is measured by thermocouple vacuum gage TVG (CVC G.TC-004) whose output is monitored by meter relay MRy (Weston 1092 Sensitrol) which is set to close if the pressure rises above about 0.2 torr. This energizes control relay CRy (Potter & Brumfield KA5Y 120VAC SPDT) cutting off power to solenoid-operated fore line valve Vf (Cenco 94280-4 Norm. Closed) which closes to prevent further leakage of air into the diffusion pump

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