Bluefors LD Trainer
Offline simulation
CRYOGENICS LAB / DILUTION REFRIGERATION

Run a dilution refrigerator.

Use the simulated controller to follow helium from storage to circulation, and see where millikelvin cooling comes from.

    50 K stage295 K
    4 K stage295 K
    Still295 K
    Cold plate295 K
    Mixing chamber295 K
    01 / COMMANDS

    Controller

    Standby
    Standby · 6 slides

    Ready to evacuate the insulating vacuum can.

    Circulation controls

    Locked

    Relative training controls. Available in circulation.

    02 / FLOW DIAGRAM

    Where the helium goes

    Mixture stored
    Swipe to trace the pipes
    Bluefors LD-style dilution refrigerator training schematic The warm gas handling system is on the left. A cutaway of the cryostat on the right shows the incoming concentrated stream, the outgoing dilute stream through their common heat exchanger, and vapor returning from the still to the warm pumps. The pulse tube and insulating vacuum have separate circuits. Select a component for its explanation. Warm gas handling Cryostat cutaway ROOM TEMPERATURE · HELIUM MIXTURE LOOP THERMAL STAGES · DILUTION UNIT Insulating vacuum Cold stages and thermal anchors 50 K flange 4 K flange Cold plate Mixture storage tank Mixture ³He / ⁴He Pulse tube compressor and cold head Pulse tube COMPRESSOR Cold trap / purifier Cold trap PURIFIER Main circulation pumps Main pumping TURBO + SCROLL Insulating vacuum service pumping Vacuum pump SERVICE MANIFOLD Condensing line Condensing line PRECOOL + EXPANSION Still and still flange Still ³He-rich vapor Still flange typically 0.6–0.9 K Counterflow heat exchangers Counterflow exchangers Mixing chamber and sample stage Rich phase Dilute phase Mixing volume Mixing chamber Sample stage Charge Recovery Still vapor return Mixture inlet Pulse-tube service loop Vacuum line Dilute ↑ Cold feed ↓ Vacuum service and pulse tube are separate circuits.
    Warm mixture Cold inlet Liquid return Still vapor Separate services
    Storage pathIsolated
    Condensing pathClosed
    Still returnClosed
    Vacuum serviceStandby
    COMPONENT INSPECTOR Mixing chamber

    03 / CURRENT LESSON

    Ready at room temperature

    Vacuum insulationNot evacuated
    Mixture in loop0%
    Relative flow0%
      04 / MIXING CHAMBER

      The dilution interface

      Concentrated · ³He-rich Dilute · ⁴He-rich ³He Mixture is still in storage

      The coldest stage is where ³He crossing into the dilute liquid absorbs heat.

      05 / THERMAL RESPONSE

      Simulated temperature history

      0.0 s simulated
      50 K4 KStillCold plateMixing chamber
      Model scope and sources

      The topology is a functional LD-family teaching schematic. The controller actions are training presets. Valve names, timing, and interlocks are illustrative. Real equipment follows its own controller, configuration, and lab procedures.

      Temperatures come from a reduced thermal model and run on accelerated time. The model uses relative mixture inventory and flow. It does not resolve pressures, pump curves, composition evolution, detailed precool cycles, or hardware interlocks. The pulse tube and the dilution mixture are separate closed circuits. The vacuum circuit removes air from the insulating can.