On a diffusion pump of super heated jets

S. Kobayashi

doi:10.3131/jvsj1950.4.154

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077967 ◽

1977 ◽

Vol 35 ◽

pp. 68-69

Author(s):

N. Yoshimura ◽

K. Shirota ◽

T. Etoh

Keyword(s):

Electron Microscope ◽

High Speed ◽

High Performance ◽

High Vacuum ◽

Vacuum System ◽

Pump System ◽

Pumping System ◽

Diffusion Pump ◽

Almost All ◽

Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

Download Full-text

A Freeze Shadow Technique for the Preparation of Soft Paint Latexes for Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079097 ◽

1977 ◽

Vol 35 ◽

pp. 314-315

Author(s):

Earl R. Walter ◽

Glen H. Bryant

Keyword(s):

Sample Preparation ◽

High Vacuum ◽

Vacuum System ◽

Latex Particles ◽

New Methods ◽

Diffusion Pump ◽

Film Forming ◽

Routine Basis ◽

Distribution Studies ◽

Preparation Techniques

With the development of soft, film forming latexes for use in paints and other coatings applications, it became desirable to develop new methods of sample preparation for latex particle size distribution studies with the electron microscope. Conventional latex sample preparation techniques were inadequate due to the pronounced tendency of these new soft latex particles to distort, flatten and fuse on the substrate when they dried. In order to avoid these complications and obtain electron micrographs of undistorted latex particles of soft resins, a freeze-dry, cold shadowing technique was developed. The method has now been used in our laboratory on a routine basis for several years.The cold shadowing is done in a specially constructed vacuum system, having a conventional mechanical fore pump and oil diffusion pump supplying vacuum. The system incorporates bellows type high vacuum valves to permit a prepump cycle and opening of the shadowing chamber without shutting down the oil diffusion pump. A baffeled sorption trap isolates the shadowing chamber from the pumps.

Download Full-text

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

Download Full-text

Voids in Quenched Nickel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101074 ◽

1968 ◽

Vol 26 ◽

pp. 266-267

Author(s):

J. J. Laidler

Keyword(s):

Electron Beam ◽

Ambient Temperature ◽

Cooling Rate ◽

Three Dimensional ◽

Cooling Curve ◽

Polycrystalline Nickel ◽

Quenching Temperature ◽

Long Tail ◽

Diffusion Pump

The presence of three-dimensional voids in quenched metals has long been suspected, and voids have indeed been observed directly in a number of metals. These include aluminum, platinum, and copper, silver and gold. Attempts at the production of observable quenched-in defects in nickel have been generally unsuccessful, so the present work was initiated in order to establish the conditions under which such defects may be formed.Electron beam zone-melted polycrystalline nickel foils, 99.997% pure, were quenched from 1420°C in an evacuated chamber into a bath containing a silicone diffusion pump fluid . The pressure in the chamber at the quenching temperature was less than 10-5 Torr . With an oil quench such as this, the cooling rate is approximately 5,000°C/second above 400°C; below 400°C, the cooling curve has a long tail. Therefore, the quenched specimens are aged in place for several seconds at a temperature which continuously approaches the ambient temperature of the system.

Download Full-text