The MINERVA superconducting linac at SCK CEN will host 30 SRF cryomodules operating in He II at 2 K, each with a distinct dynamic heat load depending on its position along the linac. The cryoplant will provide the refrigeration capacity for the system, whereas the individually controlled service to each cryomodule will be handled by the Cryogenic Distribution Backbone (QDB), enabling independent flow regulation, bath pressure control, and mode management.
We present the QDB design, instrumentation, and control strategy through several topics: system scenarios, including a 10 K standby state and the transitions between 2 K standby and 2 K linac operation; pressure regulation of the cavity He II return circuit, including the selection of pressure sensors for very-low-pressure helium service; flow estimation using a state observer combining strategically placed flowmeters and fast pressure sensors to track the mass flow of individual cryogenic cells; and a temperature-dependent protection strategy.

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