Beam and SKS spectrometers at the K1.8 beam line

High-resolution spectrometers for both incident beams and scattered particles have been constructed at the K1.8 beam line of the Hadron Experimental Facility at J-PARC. A point-to-point optics is realized between the entrance and exit of QQDQQ magnets for the beam spectrometer. Fine-pitch wire chamber trackers and hodoscope counters are installed in the beam spectrometer to accept a high rate beam up to 107 Hz. The superconducting kaon spectrometer for scattered particles was transferred from KEK with modifications to the cryogenic system and detectors. A missing-mass resolution of 1.9 ± 0.1 MeV/c2 (FWHM) was achieved for the ∑ peaks of (π±, K+) reactions on a proton target in the first physics run of E19 in 2010

ICRF Plasma Production with Hydrogen Minority Heating in Uragan-2M and Large Helical Device

ORCID　0000-0003-4948-0896This report compares results ion-cyclotron range of frequencies (ICRF) plasma production at hydrogen minority regime in Uragan-2M (U-2M) and Large Helical Device (LHD). The condition of the presence of the fundamental harmonic ion cyclotron resonance zone for the hydrogen inside the plasma column should be fulfilled for this method. The scenario is successful at both machines and weakly sensitive to the variation of the hydrogen concentration in the H2+He gas mixture. It should be noted that at LHD the start up is slower than at U-2M. The comparison of plasma production in ICRF with hydrogen minority at U-2M and LHD indicate that this scenario can be scaled to larger stellarator devices. The experiments made are the base for the proposal for usage this scenario for plasma production in ICRF at Wendelstein 7-X at magnetic field reduced to 1.7 T

ICRF Plasma Production with the W7-X Like Antenna in the Uragan-2M Stellarator

The results of the plasma start-up with ICRH of U-2M RF discharges in H2+He mixture with newly implemented controlled gas H2 concentration are presented. The W7-X like ICRH antenna operated in monopole phasing with applied RF power of ∼ 100 kW. We investigated plasma start-up in the pressure range p = 6×10−4 - 9×10−2 Pa. Plasma production with an average density of up to Ne ∼ 1013 cm−3 was observed at frequencies the fundamental harmonic of the hydrogen cyclotron frequency