Development of the bunch shape monitor for the H beam with 3 MeV using the carbon-nano tube wire

Kitamura, Ryo   ; Futatsukawa, Kenta*; Hayashi, Naoki  ; Hirano, Koichiro  ; Miyao, Tomoaki*; Moriya, Katsuhiro  ; Nemoto, Yasuo*; Oguri, Hidetomo  

In the linac of the Japan Proton Accelerator Research Complex, the bunch shape monitor (BSM) is being developed to tune the longitudinal beam matching between the accelerating cavities. When the beam irradiates the tungsten (W) wire in the BSM, the secondary electrons are emitted and extracted to the BSM in order to measure the bunch size of the H beam. However, the W wire is less resistant to the high-intensity H beam from the RFQ. Therefore, the BSM using the Carbon-Nano Tube wire (CNT-BSM) has been developed. The discharge from the CNT wire is the problem for the operation. To suppress the discharge, the baking process was introduced. Then, we succeeded in applying the high voltage to the CNT wire without the discharge. The signal responses from the W and CNT wires are being tested using the thermal electrons. We will reports the current status of the development and future prospects.