AIDT 온디바이스 STEM 제만 슬로워(Zeeman Slower) 원자 빔 감속 서보 엔진

using System;
using System.Runtime.CompilerServices;

namespace ZeliDesk.Stem.ZeemanSlower
{
    public readonly ref struct ZeemanSlowerState
    {
        public readonly double ExitVelocityMps;      // 출구 원자 속도 v_exit (m/s)
        public readonly double PeakMagneticFieldG;   // 최대 자기장 B_max (Gauss)
        public readonly double LaserDecelerationA;   // 원자 감속도 a (m/s^2)
        public readonly double ScatteringRatePhotonS;// 자발 방출 광자 산란율 (photons/s)
        public readonly bool IsMotCaptureReady;      // MOT 포획 가능 속도 도달 여부
        public readonly double SolenoidCurrentAmps;  // 메인 코일 구동 전류 (A)

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public ZeemanSlowerState(double vExit, double bMax, double acc, double scatterRate, bool captureReady, double current)
        {
            ExitVelocityMps = vExit;
            PeakMagneticFieldG = bMax;
            LaserDecelerationA = acc;
            ScatteringRatePhotonS = scatterRate;
            IsMotCaptureReady = captureReady;
            SolenoidCurrentAmps = current;
        }
    }

    public ref struct ZeemanSlowerEngine
    {
        private const double HBar = 1.054571817e-34;
        private const double MuB = 9.2740100783e-24; // J/T
        private const double MassRb87 = 1.4431606e-25; // kg
        private const double GammaRb87 = 2.0 * Math.PI * 6.065e6; // rad/s (D2 line)
        private const double WavelengthRb = 780.241e-9; // m

        private readonly double _initialVelocityMps; // 초기 열 속도 (m/s, ~500 m/s)
        private readonly double _slowerLengthM;      // 슬로워 물리적 길이 L (m, 예: 0.85 m)
        private double _laserDetuningMhz;            // 레이저 적색 편이 (MHz)
        private double _coilCurrentAmps;             // 솔레노이드 구동 전류 (A)

        public ZeemanSlowerEngine(double v0 = 500.0, double lengthM = 0.85, double initDetuningMhz = -400.0)
        {
            _initialVelocityMps = v0;
            _slowerLengthM = lengthM;
            _laserDetuningMhz = initDetuningMhz;
            _coilCurrentAmps = 25.0; // 25 A
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public ZeemanSlowerState StepServo(double currentAdjustmentAmps, double laserPowerIntensityRatio, double dtSec)
        {
            _coilCurrentAmps = Math.Clamp(_coilCurrentAmps + currentAdjustmentAmps, 5.0, 60.0);

            // 1. 최대 이론 감속도 a_max 계산 (m/s^2)
            // a_max = (hbar * k * Gamma) / (2 * M)
            double k = 2.0 * Math.PI / WavelengthRb;
            double aMax = (HBar * k * GammaRb87) / (2.0 * MassRb87); // ~1.1 x 10^5 m/s^2

            // 2. 포화도 파라미터 s0에 따른 유효 감속도
            double s0 = Math.Clamp(laserPowerIntensityRatio, 0.5, 10.0);
            double eta = Math.Clamp(s0 / (1.0 + s0) * 0.70, 0.2, 0.85); // 안전 감속 계수
            double actualAcc = eta * aMax;

            // 3. 출구 속도 계산 v_exit = sqrt(v0^2 - 2 * a * L)
            double vSquared = _initialVelocityMps * _initialVelocityMps - 2.0 * actualAcc * _slowerLengthM;
            double vExit = Math.Sqrt(Math.Max(vSquared, 0.0));

            // 4. 최대 필요 테이퍼 자기장 B_max (Gauss)
            // B0 = hbar * k * v0 / mu_B (Tesla -> Gauss: 1T = 10000G)
            double bMaxTesla = (HBar * k * _initialVelocityMps) / MuB;
            double bMaxGauss = bMaxTesla * 10000.0 * (_coilCurrentAmps / 25.0);

            // 5. MOT 포획 판정 (통상 v_exit < 35 m/s)
            bool isCaptureReady = (vExit <= 35.0);

            // 6. 광자 산란율 (photons/s)
            double scatterRate = (GammaRb87 * 0.5) * (s0 / (1.0 + s0));

            return new ZeemanSlowerState(
                vExit: vExit,
                bMax: bMaxGauss,
                acc: actualAcc,
                scatterRate: scatterRate,
                captureReady: isCaptureReady,
                current: _coilCurrentAmps
            );
        }
    }
}