{
  "source": {
    "author": "J. Marlin Smith",
    "title": "Experiments on H2-O2 MHD Power Generation",
    "report": "NASA-TM-81424",
    "year": 1980,
    "ntrs_id": "19800008626",
    "printed_pages_examined": "2-8",
    "pdf_pages_examined": [2, 3, 4, 7, 8, 9],
    "local_sha256": "5C7C122E27A840E556E600DC1BCA05AC31FF0F96674572D611827B8BE0B391E6"
  },
  "evidence_type": "Hot-gas Hall MHD generator component experiment; not an integrated propulsion-loop test",
  "nominal_conditions": {
    "combustion_stagnation_pressure_atm": 10,
    "mass_flow_kg_s": 0.5,
    "thermal_input_MW": 7,
    "peak_magnetic_field_T": 5,
    "entrance_Mach": 2,
    "duct_length_cm": 58,
    "run_duration_s": 5,
    "exhaust_boundary": "Water-quenched and discharged at atmospheric pressure"
  },
  "reported_maximum_generator_outputs_kW": [87.5, 153],
  "calculated_gross_output_over_thermal_input": {
    "area_ratio_2_56_decimal_fraction": 0.0125,
    "area_ratio_4_decimal_fraction": 0.021857142857142856,
    "area_ratio_2_56_base12": "0.01(9724)",
    "area_ratio_4_base12_exact_fraction": "C9/4074",
    "base12_digit_convention": "A=10, B=11; parentheses mark repeating digits",
    "boundary_note": "Gross generator output divided by stated burner thermal input; not net cycle/plant efficiency"
  },
  "source_reported_limits": [
    "4:1 duct shock appeared at combustion pressures at or below about 7 atm, even without power extraction; stronger field moved the shock upstream",
    "Open-circuit tests broke down above about 50 V per insulator after roughly 2.5 seconds of seed injection; anode-side insulator damage observed",
    "Proposed topping-plant target required about 40% enthalpy extraction; report says practical achievement remained open",
    "Atmospheric-pressure exhaust test did not establish performance at proposed low sub-atmospheric outlet pressure",
    "No propulsion accelerator, aircraft bus, auxiliary-load or vehicle-force closure"
  ],
  "redraw_status": "Existing Site bar graph is a DMGB redraw; this update adds evidence context, does not copy the NASA source figures"
}