TF cooling water
Because of the significant amount of ohmic power dissipated in the toroidal field magnets (~5kA into 148mΩ is ~3.75MW) with the upgraded power supply arrangement, the LTX-β upgrade included an enhancement of the cooling system from forced air to pressurized (~60PSI) chilled water.
Chiller
The water chiller is in the south-east corner of the test cell, near the Thomson scattering optical table.
Powering on/off the chiller simply requires pressing the power button. The temperature should be set to 65°F.
Note that the chiller can take several seconds to fully turn on/off, so the flow meter may not show an immediate change.
Filtration
In order to avoid current flowing from the TF coil to ground through (or breakdown within) the water cooling system, the water conductivity should be kept to 2μS or less. The filtration system is in the south-east corner of the test cell, above the water chiller.
August 2019
It was dicovered during the TF coil inductive hipot testing of a spurious electrostatic potential and seemingly low resistivity when the TF cooling water system was connected. This prompted an examination of the system, which found that 1. the water level in the reservoir was extremely low, 2. the water conductivity was 111μS (compared to 280μS for water from the hallway water cooler), 3. there was no deionizing filter in the system (only two particulate filters), and 4. all visible parts of the cooling water system were coated with a brown residue (visible in Fig. N) which also saturated both particulate filters.
On August 7th-8th, the system was flushed and refilled with deionized water several times and after a thorough cleaning of the filter drums, water was run through a fresh particulate filter for a day, bringing the conductivity down to about 15μS. The filter did not seem to pick up any significant amount of the brown residue. The addition of a deionizing filter brought the conductivity down to about 2μS within hours, but the filter shed resin particles into the water line, so a particulate filter was added downstream of the deionizing filter. As of August 9th, after swapping in a high-purity deionizing filter, the conductivity was measured at 0.8μS, well within the target range.
Flow Meter
The flow meter is in the south-east corner of the test cell, to the right (facing the wall) of the filters. In a zero-flow state, the bob rests at the bottom of the flow meter cavity, but it rises to roughly 6GPH (read from the top of the bob) when running.
Related Pages
Water Systems
Cooling water: TF magnets | Vacuum vessel | Thomson scattering | Robicons
