Non-thermal equilibrium effect on plasma window with large diameter

摘要: The disposal of high-level radioactive waste (HLW) is a serious social problem. To address it, a transmutation scheme of long-lived fission products (LLFP) employing a high-power accelerator, which provides deuteron beams of 400 MW, was proposed in the Im-PACT Fujita program. 1) In such a system, a beam window, which separates the accelerator and target region, is considered one of the key issues. A plasma window (PW), 2) which exploits a large pressure gradient generated by an arc plasma filling the discharge channel, is considered a promising candidate. However, the first PW invented by Hershcovitch2) had an aperture of 2.36 mm, while the beam-spot size required in our case is 100 mm or larger.Therefore, we developed a PW with a maximum diameter of 20 mm, as shown in Fig. 1, and demonstrated conductance reduction by the PW. 3) Furthermore, a comparison between the achieved cell …