2 MEV ELECTRON IRRADIATION AND THERMAL ANNEALING OF PURE COPPER AT LOW TEMPERATURE
Radiation damage studies of pure copper specimens were performed by using a Van de Graaff accelerator to supply energetic electrons of 2 Mev. The irradiating electrons were magnetically deflected so that the electron beam bombarded a well-defined rectangular area. A method was also developed for determining the location of the electron beam with respect to apecimen position. A 25-liter liquid helium cryostat maintained the necessary low temperature. In order to control the annealing temperature, a thermal switch was used which governed heat transfer according to the admission or evacuation of helium exchange gas. The theoretical aspects and experimental behavior of all cryogenic equipment are discussed. One major problem of lowtemperature irradiation of metal samples concerns the thermal conduction between specimen and specimen holder. It was found that it is practical to use the helium exchange gas technique for improving this thermal contact. Estimates of the degree of thermal contact between the specimen and its holder were also possible because of the particular electrical circuit which was used in the experimental chamber. Resistance measurements were obtained by the potentiometric method. Reliable potential readings were obtained to approximately 10/sup -8/ volts for the high purity copper samples which were irradiated. The recovery data pertaining to the relative change of resistivity due to annealing make use of a procedure which reduced systematic experimental errors. Results of this work are in the region where multiple defect production occurs during irradiation. The number of multiple defects produced during 2 Mev electron irradiation was obtained from existing theories. This enabled an experimental evaluation of the magnitude of resistivity change per atomic percent of Frenkel defects. Good agreement is obtained by this technique of evaluation when results are compared to previous experimental determinations. Thus, the simple theory of atomic displacements suffices for explaining results of this work. The lowtemperature substages of high purity copper, which are associated with the recovery of Frenkel defects, were measured following each 2-Mev electron irradiation. The initial four substages of stage I recovery were evident from this work. The results associated with close pair Frenkel defect recovery show that a correlation exists between prior experimental work performed by lower energy electron and l0-Mev deuteron bombardments. It is evident that each intrinsic substage possesses a very definite dependence upon irradiation energy. (Dissertation Abstr., 23: No. 3, 1982)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-17-002038
- OSTI ID:
- 4784695
- Resource Relation:
- Other Information: Thesis. Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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STAGE I RECOVERY SPECTRUM OF PURE COPPER IRRADIATED WITH ELECTRONS OVER THE RANGE 1.25 TO 3.25 Mev
Related Subjects
ANNEALING
ATOMIC MODELS
CIRCUITS
CONTROL
COPPER
CRYOGENICS
DEFECTS
DEUTERON BEAMS
ELECTRIC CONDUCTIVITY
ELECTRIC POTENTIAL
ELECTRON BEAMS
ENERGY
ERRORS
FRENKEL DEFECTS
HEAT TRANSFER
HELIUM
IRRADIATION
LATTICES
LIQUIDS
LOW TEMPERATURE
MAGNETIC FIELDS
MEASURED VALUES
RADIATION DOSES
SWITCHES
THERMAL CONDUCTIVITY
VAN DE GRAAFF ACCELERATORS
VARIATIONS