Development of compact high energy proton acceleration technology by using a complex target

Laser acceleration technology, which is realized by focusing an ultra-intense laser pulse on a thin foil, can substantially reduce current hugh accelerators. In this project, we have developed compact proton acceleration technology based on laser acceleration technology for popularization of the proton cancer therapy system. The most urgent issue in this field is to develop a technology, which can significantly enhance the proton energy. We have considered a way to enhance acceleration field in the plasma by utilizing target structure. Especially, in the proposed VSDL target, completely different type of acceleration mechanism can occur compared with single layer target, which is expected to enhance the proton energy 2-4 times