{
  "title": "Pulsed air-plasma accelerator: reported time-of-flight comparison",
  "source": {
    "authors": [
      "Ethan Horstman",
      "Adrian Woodley",
      "Thomas C. Underwood"
    ],
    "journal": "Journal of Applied Physics",
    "volume": 138,
    "article": "063303",
    "year": 2025,
    "doi": "10.1063/5.0273140",
    "open_preprint": "https://arxiv.org/abs/2503.08889",
    "figure": "Figure 10 and Section 4.2"
  },
  "data_origin": "The paper's prose reports approximately 55 km/s at about 60 micrograms and approximately 20 km/s at about 120 micrograms, with 28 J charging energy and about 7 kA peak current. Values are transcribed as approximate, not digitized from the figure.",
  "method": "High-speed broadband camera imaging at 10 million frames per second; velocity inferred by fitting plume leading-edge position over time. A separate ballistic pendulum measured impulse bit.",
  "conditions": {
    "propellant": "air",
    "environment": "laboratory vacuum chamber",
    "charging_energy_J": 28,
    "peak_current_kA_approx": 7,
    "downstream_mass_ug_approx": [
      60,
      120
    ],
    "shots_or_cases": "The regime map summarizes 26 operating combinations; the article does not identify a repeated-sample count for each of these two time-of-flight cases in the prose."
  },
  "interpretation_limits": [
    "The time-of-flight method tracks the luminous plume leading edge and is not a mass-weighted average exhaust speed.",
    "The reported values are approximate; no uncertainty bars for these two points are stated in the paper text.",
    "The 60 microgram case is described as weakly unstable magneto-deflagration; the 120 microgram case changes to magneto-detonation.",
    "A higher leading-edge velocity alone does not establish greater thrust, overall energy efficiency, longer life, or complete vehicle performance.",
    "At lower gas loading, the paper reports a transition near 15 micrograms at 40 J where electrode ablation can contribute to the accelerated mass; the high specific-impulse claims near that regime need the erosion caveat.",
    "This was a gas-fed laboratory accelerator operating on air in vacuum, not an in-orbit air-breathing spacecraft demonstration and not atmospheric hypersonic propulsion.",
    "The paper's stated long-term VLEO use is a potential application; capture, compression, spacecraft power, drag balance, erosion life, and integrated operation remain separate system questions.",
    "The graph uses reported approximate points only, with no interpolation between them."
  ],
  "figure_status": "Original vector redraw and schematic based on described apparatus and article-reported prose values; not a reproduction of the paper's figures.",
  "generated": "2026-10-04",
  "reported_summary_discrepancy": {
    "abstract": "5% to 35% over approximately 70 to 10 micrograms",
    "detailed_results": "10% to 35% over approximately 70 to 15 micrograms",
    "figure_11": "Sharp increase near 15 micrograms may involve transition to ablative operation",
    "resolution": "Unresolved within the article; retain both stated summaries and do not select one",
    "source_sections": [
      "Abstract",
      "Section 4.2",
      "Figure 11 caption"
    ]
  },
  "conditional_endpoint_arithmetic": {
    "source_reported_ranges": {
      "impulse_bit_microN_s": [
        334,
        140
      ],
      "downstream_mass_micrograms": [
        70,
        15
      ],
      "specific_impulse_s": [
        100,
        2000
      ]
    },
    "formula": "Isp = Ibit / (g0 * m_dwn)",
    "assumption": "Provisionally pair the first stated impulse and mass endpoints, and then the second endpoints. The article does not publish a point-by-point numerical table establishing these exact pairs.",
    "g0_m_s2": 9.80665,
    "calculated_pairs": [
      {
        "Ibit_microN_s": 334,
        "m_dwn_micrograms": 70,
        "Isp_decimal_s_approx": 486.5503073351829,
        "Isp_base12_s_truncated_8_places": "346.672B20A9"
      },
      {
        "Ibit_microN_s": 140,
        "m_dwn_micrograms": 15,
        "Isp_decimal_s_approx": 951.735132112733,
        "Isp_base12_s_truncated_8_places": "673.89A38488"
      }
    ],
    "result": "Both conditional calculations fall inside the article’s broad 100–2000 s range. This neither establishes the exact point pairing nor resolves the abstract/body utilization and mass-range discrepancy.",
    "condition_separation": "Do not combine with the ~55 km/s Figure 10 prose value: that case is about 28 J / 7 kA, whereas Figure 11 is 40 J / 8 kA.",
    "rounding": "Decimal values shown to 2 places in site prose; base-12 values truncate after 8 fractional digits and are notation conversions only."
  }
}