t been investigated with regard to light spectra by the electron beam (the distribution of the intensity of light as a function of wavelength), and data that express the relationship between the light spectrum and the crystal condition were few, which are necessary for the analysis of the material condition.
First, we are moving forward with constructing a new database. Because the color of the light emitted when the electron beam strikes differs depending upon the material, we are investigating in what color will the light shine, and to what color will that color change when the crystal’s condition changes. We are collecting data relating to these processes. To date, for example, erbium oxide, which is used to insulate the inner piping (see number 267), emits purple, green, and red lights together. But we have learned that when the arrangement of the atoms becomes disordered, red-colored light will weaken. Further, similarly, yttrium oxide, which is a candidate for the coating material, ordinarily shines in a mix of purple, blue, and green colors. But when the order of the atoms becomes disturbed, ultraviolet radiation and the light of the orange and red colors are strengthened.
It is possible to observe this type of light spectrum in short blocks of time. Although the material has the same name, ceramic materials may vary in quality when purchased from different companies because the condition of the crystal changes depending upon the firing condition (baking temperature, length of time, etc.). By utilizing the CL method and the database, we can promptly evaluate that quality. Further, one can also examine over a short period of time the condition of ceramics materials that one has produced experimentally. In the future, in order to be able to utilize the CL method in the test for evaluating conditions of materials under the condition of the fusion reactor, we will widen further the targets for observation of the light spectrum (that is, make still more materials and crystals the object of investigation), collect and store data, and enrich the database.