98 lines
2.9 KiB
Rust
98 lines
2.9 KiB
Rust
//! H⁻ 束缚-自由截面。
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//!
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//! 重构自 TLUSTY `sbfhmi.f`
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use crate::math::ylintp;
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/// H⁻ 束缚-自由截面。
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///
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/// 计算负氢离子的束缚-自由吸收截面。
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///
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/// # 参数
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///
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/// * `fr` - 频率
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///
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/// # 返回值
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///
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/// H⁻ 束缚-自由截面 (cm²)。
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///
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/// # 备注
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///
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/// 数据来自 Mathisen (1984)，基于 Wishart (1979) 和 Broad & Reinhardt (1976)。
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/// 阈值频率: 1.82365e14 Hz。
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pub fn sbfhmi(fr: f64) -> f64 {
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// 波长数据 (nm)
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const WBF: [f64; 85] = [
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18.00, 19.60, 21.40, 23.60, 26.40, 29.80, 34.30,
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40.40, 49.10, 62.60, 111.30, 112.10, 112.67, 112.95, 113.05,
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113.10, 113.20, 113.23, 113.50, 114.40, 121.00, 139.00, 164.00,
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175.00, 200.00, 225.00, 250.00, 275.00, 300.00, 325.00, 350.00,
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375.00, 400.00, 425.00, 450.00, 475.00, 500.00, 525.00, 550.00,
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575.00, 600.00, 625.00, 650.00, 675.00, 700.00, 725.00, 750.00,
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775.00, 800.00, 825.00, 850.00, 875.00, 900.00, 925.00, 950.00,
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975.00, 1000.00, 1025.00, 1050.00, 1075.00, 1100.00, 1125.00, 1150.00,
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1175.00, 1200.00, 1225.00, 1250.00, 1275.00, 1300.00, 1325.00, 1350.00,
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1375.00, 1400.00, 1425.00, 1450.00, 1475.00, 1500.00, 1525.00, 1550.00,
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1575.00, 1600.00, 1610.00, 1620.00, 1630.00, 1643.91,
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];
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// 截面数据 (10^18 cm²)
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const BF: [f64; 85] = [
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0.067, 0.088, 0.117, 0.155, 0.206, 0.283, 0.414,
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0.703, 1.24, 2.33, 11.60, 13.90, 24.30, 66.70, 95.00,
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56.60, 20.00, 14.60, 8.50, 7.10, 5.43, 5.91, 7.29,
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7.918, 9.453, 11.08, 12.75, 14.46, 16.19, 17.92, 19.65,
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21.35, 23.02, 24.65, 26.24, 27.77, 29.23, 30.62, 31.94,
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33.17, 34.32, 35.37, 36.32, 37.17, 37.91, 38.54, 39.07,
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39.48, 39.77, 39.95, 40.01, 39.95, 39.77, 39.48, 39.06,
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38.53, 37.89, 37.13, 36.25, 35.28, 34.19, 33.01, 31.72,
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30.34, 28.87, 27.33, 25.71, 24.02, 22.26, 20.46, 18.62,
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16.74, 14.85, 12.95, 11.07, 9.211, 7.407, 5.677, 4.052,
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2.575, 1.302, 0.8697, 0.4974, 0.1989, 0.0,
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];
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const FR_THRESHOLD: f64 = 1.82365e14;
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if fr > FR_THRESHOLD {
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let wave = 2.99792458e17 / fr;
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ylintp(&WBF, &BF, wave) * 1e-18
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} else {
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0.0
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use approx::assert_relative_eq;
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#[test]
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fn test_sbfhmi_below_threshold() {
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// 低于阈值频率
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let result = sbfhmi(1e14);
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assert_relative_eq!(result, 0.0, epsilon = 1e-20);
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}
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#[test]
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fn test_sbfhmi_above_threshold() {
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// 高于阈值频率
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let result = sbfhmi(2e15);
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assert!(result > 0.0);
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assert!(result < 1e-16); // 截面量级
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}
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#[test]
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fn test_sbfhmi_visible() {
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// 可见光范围 (~5e14 Hz)
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let result = sbfhmi(5e14);
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assert!(result > 0.0);
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}
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#[test]
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fn test_sbfhmi_uv() {
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// 紫外范围
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let result = sbfhmi(1e15);
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assert!(result > 0.0);
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}
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}
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