Calibrated Cernox vs. LHe Vapor Pressure dT=10 mK He Condensation ~ 4.6 K (1.4 atm) T min ~ 3.7 K (0.6 atm) CX-1050SD-1.4D
Absorber Cooling Test 20 L Absorber was filled ~1.4 L L-H2.
20 l Absorber cooling test at KEK (1) Assemble *Level sensors at bottom, 2 Cernox and 1 PtCo on body *Lead wires pass through at the LH2 condenser *window seal; d=1 mm Indium (1 loop) *8 G10 (t=5) supports *MLI set; Al-Mylar 9 x5 + Nylon Mesh x6 1 layer on windows and G10 supports 4 layers on body ~2 layers on flexible pipes. (2) Vacuum and Leak Test *Leak at 300K disassemble found pinhole at a Helicoflex KF25 changed recovered *vacuum; 3 x 10^(-6) Torr after 3 days, 300K
(3) Cooling Test #1 Sep-14, ‘06 *cryocooler cooling 82 hrs; 300 20K *solid air blocking at the 1 st stage heat exchanger H2 impurity after 2 years operation for LH2 target changed gas-H2 1.5 atm in the 2,000 L tank (4) Cooling Test #2 (same assemble) Sep-22, ‘06 *restart with LN2 pre-cooling leak from N2 to vac. at ~200K stop LH2 filling *restart cryocooler w/o LN2 from 230K, takes 60 hrs from 230K to 20K *liquefied ~1.5 l H2 ( 1.5 0.9 atm 2,000 L tank) *measured H2 condensation and evaporation speed 20 l Absorber cooling test at KEK (continued)
20 l Absorber inserted to warm bore and piping LN2(LHe) outlet LH2 inlet LN2(LHe) inlet LH2 outlet
Bottom view of H2 condenser LH2 supply LH2 return LN2(LHe) return LN2(LHe) supply Kyocera 48 pin From LH2 supply line (from Absorber) To Bendix 18 pin
Insert to Vacuum Chamber Pipes with MLI ~2 layers
20 l Absorber H2 liquefaction test at KEK (LH2 1.425 l liquefied) H2 Press. (Torr) CX REF. 2nd.(ohm) CX REF. 1st. (ohm) CX0-calib. (K) *10 LH2 Temp_P. (K) *10 PtCo Abs. (K)*10 L-H2 in bodyL-H2 in pipe
20 l Absorber H2 liquefaction test at KEK LH2 GH2 Level sensors In LH2 at same time? G10 support was turned down?
Cernox vs. H2-pressure In LH2 Condenser Temperature measurements by H2 pressure is possible within error. Cernox vs. H2-pressure In Absorber Temperature by H2 pressure
Liquefaction and Vaporization of LH2 in 20 l Absorber 0.30 l / h, 2.6 W 1.33 l / h, 11.7 W 2000 l tank Cooling stop LH2 1.43 l 68 hrs to fill 20 l
(1) Cooling time (300K 20K) > 82 hrs by cryocooler only (not yet tested with LN2 pre-cooling) Needs LN2 pre-cooling (2) Condensation speed; 0.30 l / h, 2.6 W 68 hrs to fill 20L Needs better insulation to obtain shorter filling time (3) Evaporation speed ~ heat leak; 1.33 l / h, 11.7 W (2)+(3) = 14.3 W ; net cooling power at absorber LHe absorber required Q L (heat leak) < 1.5 W@4.2K LHe Absorber needs additional L-He supply ? Summary 1/2 (Absorber Cooling Test)
(1) Cooling test with LN2 pre-cooling > Cold leak test and fix the LN2 channel > Open the window and check the level sensors repair if it needs > Add PtCo thermometer on the dummy bore and in the condenser (2) Improvement of absorber insulation > design G-10 support, MLI.... * Until Q L < 1.5 W@4.2K for the LHe absorber, if possible ? * Larger cooling power margin makes shorter filling time and easier operation for the LH2 absorber. Summary 2/2 (Future Plan)