Initial Tests for Electrostatic Septum Using Carbon Nanotube Wires

Abstract

A stable 50 kW slow-extracted beam has been being delivered to the experimental hall (hadron hall) to execute various experiments on nuclear physics and elementary particle physics in J-PARC. However future experimental programs need beam powers much more than 100 kW. The slow extraction technique makes an inevitable beam loss around the electrostatic septum (ESS) using a septum to make an electric field distribution with a step function. The beam loss generated by hitting at the septum is most critical and limits the beam power. Tungsten including rhenium (W/Re) is used for the septum material for the present ESSs. If the material with a low atomic number can be used for the septum, the beam loss can be drastically reduced. We have started to develop carbon nanotube (CNT) wires for the ESS. Preliminary voltage supply test has been carried out using a test stand fabricated to investigate various basic characteristics of the CNT wire.