TY - JOUR
T1 - Performance of cold compressors in a cooling system of an R&D superconducting coil cooled with subcooled helium
AU - Hamaguchi, S.
AU - Imagawa, S.
AU - Yanagi, N.
AU - Takahata, K.
AU - Maekawa, R.
AU - Mito, T.
PY - 2006/11
Y1 - 2006/11
N2 - The helical coils of large helical device (LHD) have been operated in saturated helium at 4.4 K and plasma experiments have been carried out at magnetic fields lower than 3 T for 8 years. Now, it is considered that the cooling system of helical coils will be improved to enhance magnetic fields in 2006. In the improvement, the helical coils will be cooled with subcooled helium and the operating temperature of helical coils will be lowered to achieve the designed field of 3 T and enhance cryogenic stabilities. Two cold compressors will be used in the cooling system of helical coils to generate subcooled helium. In the present study, the performance of cold compressors has been investigated, using a cooling system of R&D coil, to apply cold compressors to the cooling system of helical coils. Actual surge lines of cold compressors were observed and the stable operation area was obtained. Automatic operations were also performed within the area. In the automatic operations, the suitable pressure of a saturated helium bath, calculated from the rotation speed of the 1st cold compressor, was regulated by bypass valve. From these results, stable operations will be expected in the cooling system of helical coils.
AB - The helical coils of large helical device (LHD) have been operated in saturated helium at 4.4 K and plasma experiments have been carried out at magnetic fields lower than 3 T for 8 years. Now, it is considered that the cooling system of helical coils will be improved to enhance magnetic fields in 2006. In the improvement, the helical coils will be cooled with subcooled helium and the operating temperature of helical coils will be lowered to achieve the designed field of 3 T and enhance cryogenic stabilities. Two cold compressors will be used in the cooling system of helical coils to generate subcooled helium. In the present study, the performance of cold compressors has been investigated, using a cooling system of R&D coil, to apply cold compressors to the cooling system of helical coils. Actual surge lines of cold compressors were observed and the stable operation area was obtained. Automatic operations were also performed within the area. In the automatic operations, the suitable pressure of a saturated helium bath, calculated from the rotation speed of the 1st cold compressor, was regulated by bypass valve. From these results, stable operations will be expected in the cooling system of helical coils.
KW - Automatic control
KW - Cold compressor
KW - Stable operation
KW - Subcooled helium
KW - Surge
UR - http://www.scopus.com/inward/record.url?scp=33846014286&partnerID=8YFLogxK
U2 - 10.1016/j.fusengdes.2006.07.052
DO - 10.1016/j.fusengdes.2006.07.052
M3 - Article
AN - SCOPUS:33846014286
SN - 0920-3796
VL - 81
SP - 2617
EP - 2621
JO - Fusion Engineering and Design
JF - Fusion Engineering and Design
IS - 23-24
ER -