Space charge behavior of XLPE/silica nanocomposites under high electric field
Space charge formation behavior is compared among crosslinked polyethylene and its two nanocomposites with silica nanofillers with and without surface treatment. By conducting a degassing treatment, we have prepared nine kinds of samples in total. As a result, it was found that the presence of cross-linking by-products suppresses space charge formation. As far as the present silica nanofillers are concerned, their addition to XLPE enhances the formation of negative space charge near the cathode.
The effects of material properties and inclusions on the space charge profiles of LDPE and XLPE
The effects of material properties and inclusions on the space charge profiles in LDPE and XLPE were examined. Whereas the charge profile in LDPE is influenced by material properties such as the degree of crystallinity and MFR, the charge profile in XLPE is influenced by inclusions in the material such as acetophenone, moisture and various kinds of phenolic antioxidant. In order to examine the effect of moisture on the creation of negative hetero-charge in XLPE, the charge profiles in LDPE and XLPE containing a non-ionic surfactant glycerol monostearate were examined. Taking into account the density of the hetero-charge in relation to the concentration of cross-linking byproducts, as well as the conductivity of pure water containing each of the cross-linking byproducts, the mechanism of hetero-charge creation in XLPE was discussed.
DESIGN CONSIDERATION TO PPM KLYSTRONS FOR INDUSTRIAL LINAC
Toshiba has been developing the C-band and X-band Periodic Permanent Magnet (PPM) focused klystron in collaboration with KEK and manufactured prototypes for the JLC project. [1] The PPM klystron has an advantage to enhance the total efficiency as a result of eliminating the electric power for the focusing magnet. From experience on the development the PPM focused klystrons for the JLC project, we plan to apply the PPM focused klystron to the medical and industrial linac. The periodic magnet focusing scheme has some technical difficulties such as stop band voltage. To design the PPM klystron for the medical and industrial linac, it is necessary to give heed to electron beam instability; so that the tube parameters of the PPM focused klystrons have some constraints. The size of the accelerator system is substantially reduced if a PPM focused klystron is used. The majority of medical and industrial linacs use frequencies of S-band range. We discuss the availability of the S-band PPM focused klystron in this paper.