Radiation cleanup of vacuum systems (radiation-induced outgassing). Final report, September 15, 1976--November 14, 1977

Radiation-induced homogeneous precipitation in Ni-Be alloys was recently observed by high voltage electron microscopy. A coupling of interstitial flux with solute Be atoms is responsible for the precipitation. The present investigation further shows that precipitation is also induced at thin foil surfaces by electron irradiation under a high vacuum.

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Annealing Of Radiation Damage in Tungsten

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069053 ◽

1970 ◽

Vol 28 ◽

pp. 412-413

Author(s):

Robert C. Rau ◽

John Moteff

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Radiation Damage ◽

Thermal Annealing ◽

Neutron Fluence ◽

Dislocation Loops ◽

Defect Clusters ◽

Polycrystalline Tungsten ◽

Transmission Electron ◽

Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

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Radiation-induced surface decomposition

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075592 ◽

1983 ◽

Vol 41 ◽

pp. 368-369

Author(s):

M. L. Knotek

Keyword(s):

Ionizing Radiation ◽

Atomic Structure ◽

Chemical Bonding ◽

Neutral Species ◽

Radiation Induced ◽

Physical And Chemical ◽

Surface Decomposition ◽

The Relationship ◽

Electron And Photon ◽

Surface Bond

Modern surface analysis is based largely upon the use of ionizing radiation to probe the electronic and atomic structure of the surfaces physical and chemical makeup. In many of these studies the ionizing radiation used as the primary probe is found to induce changes in the structure and makeup of the surface, especially when electrons are employed. A number of techniques employ the phenomenon of radiation induced desorption as a means of probing the nature of the surface bond. These include Electron- and Photon-Stimulated Desorption (ESD and PSD) which measure desorbed ionic and neutral species as they leave the surface after the surface has been excited by some incident ionizing particle. There has recently been a great deal of activity in determining the relationship between the nature of chemical bonding and its susceptibility to radiation damage.

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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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