A laser wakefield accelerator(LWFA), which can be used to accelerate electrons by interaction between high-intensity laser pulse and plasmas, has the advantage to miniaturize the system size as it can obtain in a narrow region compared with conventional systems. The characteristics of the Very High Energy Electron(VHEE) beam in LWFA has attracted much interest because of its potential application such as ultrashort x-ray source, betatron radiation, and medical applications. In particula, many researchers have recently studied the efficiency of VHEE-based cancer treatment systems for the treatment of deep-sated tumors. This result has reported that this system can minimizes damage to normal cells and efficiently remove cancer cells.
In Korea Electrotechnology Research Institute (KERI), we have studied the development of a compact cancer treatment system by 20 TW ultra-short high power laser based LWFA system. In this study, electron beams with energy of 70 and 90 MeV were obtained by ionization injection from mixed gas, helium gas containing 10 % nitrogen, and the charge were 25, 18 nC, respectively. Three-dimensional Percent Dose Distribution(PDD) of electron beam was measured by tough phantom composed of Gafchromic films. The measured PDD shows the size-preserving shape of the electron beam, known as pencil-like beam, at high energy. For comparison with experimental results, "PDD" according to depth of penetration of electron beam was calculated using GEANT4 code. The experimental results and the calculated results were in good agreement. Significantly, because of the electron beam energy spread, the PDD at relatively shallow depths, such as neat the entrance port is similar to the result of low energy beam and to the penetration results at high energy at a deep penetration depth close to the exit port. The dose per electron beam charge was obtained to be 7 cGy/nC.
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 Jaehoon Kim , Yong Hun Hwangbo and Kyung Nam Kim, Plasma Phys. Control. Fusion 60, 034008, 2018
|Working group||Laser-driven electron acceleration|