Helium Flow Meter

C53-34b-271354The Superconducting Radio Frequency (SRF) Cavities, that accelerate particles in many of the US DOE Labs, need a method of indicating their health “real-time” during use. The Helium Flow Meter, proven to work in Phase I, measures extra heat generated by contaminants inside the cavity by measuring increased evaporation of helium from the cooling bath in which the cavity is immersed. With this easily performed measurement, accelerator operators would turn down the unhealthy cavities and turn up healthy cavities, maintaining the rated beam energy of their accelerator while reducing excess radiation in the accelerator from the contaminated cavities and excessive load on the Cryogenic Plant. Conventional flow meters, with weak signals at the operating temperature of ~2 to 4 K and pressure of 0.03 atmospheres, have all been proven not to work in trials over 35 years. The Hyperboloid Helium Flow Meter uses the switch capability of a superconducting wire to turn highly resistive at ~10 K to give a strong signal. The higher the flow, which removes heat, the greater the current through an adjacent heater wire is needed to trip to the non-superconducting state. The electronics detects this changed state and software keeps track of the heater current. Phase I showed that the recorded heater current can measure the helium flow with good resolution. Phase II will install Flow Meters in the helium return gas flows of 5 of the 53 accelerating units at the Jefferson Lab’s CEBAF Accelerator. Over the two-year period, the Instrument Head, the electronics, the software and the use by Operators will be improved so that at the end of the second period, Hyperboloid will be able to offer a commercial product that the SRF Community, in the US, as well as the rest of the World, can rely on. Hyperboloid will investigate what changes to the Instrument Head are necessary to make the flow meter useful for the public purpose in the cryogenic realm where instruments are scarce. These include helium around 4 to 5 K at higher pressures and a variant where the superconducting element in the instrument head is a “high temperature” superconductor for use with cryogenic hydrogen near its boiling point of 20 K. Green Hydrogen is a product whose market is about to expand and this type of flow meter may play an important part in cryogenic storage.