EIC code displayed by LXR |
|
|
|
|||
File indexing completed on 2025-01-18 09:10:53
0001 // This file is part of the ACTS project. 0002 // 0003 // Copyright (C) 2016 CERN for the benefit of the ACTS project 0004 // 0005 // This Source Code Form is subject to the terms of the Mozilla Public 0006 // License, v. 2.0. If a copy of the MPL was not distributed with this 0007 // file, You can obtain one at https://mozilla.org/MPL/2.0/. 0008 0009 #pragma once 0010 0011 #include "Acts/Definitions/Algebra.hpp" 0012 #include "Acts/MagneticField/MagneticFieldContext.hpp" 0013 #include "Acts/MagneticField/MagneticFieldProvider.hpp" 0014 #include "Acts/Utilities/Result.hpp" 0015 0016 #include <cstddef> 0017 0018 namespace Acts { 0019 0020 /// @ingroup MagneticField 0021 // 0022 /// @class SolenoidBField 0023 /// Implements a multi-coil solenoid magnetic field. On every call, the field 0024 /// is evaluated at that exact position. The field has radially symmetry, the 0025 /// field vectors point in +z direction. 0026 /// The config exposes a target field value in the center. This value is used 0027 /// to empirically determine a scale factor which reproduces this field value 0028 /// in the center. 0029 /// 0030 /// E_1(k^2) = complete elliptic integral of the 1st kind 0031 /// E_2(k^2) = complete elliptic integral of the 2nd kind 0032 /// 0033 /// E_1(k^2) and E_2(k^2) are usually indicated as K(k^2) and E(k^2) in 0034 /// literature, 0035 /// respectively 0036 /// _ 0037 /// 2 / pi / 2 2 2 - 1 / 2 0038 /// E (k ) = | ( 1 - k sin {theta} ) dtheta 0039 /// 1 _/ 0 0040 /// 0041 /// _ ____________________ 0042 /// 2 / pi / 2| / 2 2 0043 /// E (k ) = | |/ 1 - k sin {theta} dtheta 0044 /// 2 _/ 0 0045 /// 0046 /// k^2 = is a function of the point (r, z) and of the radius of the coil R 0047 /// 0048 /// 2 4Rr 0049 /// k = --------------- 0050 /// 2 2 0051 /// (R + r) + z 0052 /// Using these, you can evaluate the two components B_r and B_z of the 0053 /// magnetic field: 0054 /// _ _ 0055 /// mu I | / 2 \ | 0056 /// 0 kz | |2 - k | 2 2 | 0057 /// B (r, z) = ----- ------ | |-------|E (k ) - E (k ) | 0058 /// r 4pi ___ | | 2| 2 1 | 0059 /// | / 3 |_ \2 - 2k / _| 0060 /// |/ Rr 0061 /// 0062 /// _ _ 0063 /// mu I | / 2 \ | 0064 /// 0 k | | (R + r)k - 2r | 2 2 | 0065 /// B (r,z) = ----- ---- | | -------------- | E (k ) + E (k ) | 0066 /// z 4pi __ | | 2 | 2 1 | 0067 /// |/Rr |_ \ 2r(1 - k ) / _| 0068 /// 0069 class SolenoidBField final : public MagneticFieldProvider { 0070 public: 0071 struct Cache { 0072 /// @brief Constructor with magnetic field context 0073 Cache(const MagneticFieldContext& /*mctx*/) {} 0074 }; 0075 0076 /// Config struct for the SolenoidBfield. 0077 struct Config { 0078 /// Radius at which the coils are located. 0079 double radius; 0080 /// Extent of the solenoid in z. It goes from 0081 /// -length/2 to +length/2 by convention 0082 double length; 0083 /// The number of coils that make up the solenoid 0084 std::size_t nCoils; 0085 /// The target magnetic field strength at the center. 0086 /// This will be used to scale coefficients 0087 double bMagCenter; 0088 }; 0089 0090 /// @brief the constructor with a shared pointer 0091 /// @note since it is a shared field, we enforce it to be const 0092 /// @tparam bField is the shared BField to be stored 0093 SolenoidBField(Config config); 0094 0095 /// @brief Retrieve magnetic field value in local (r,z) coordinates 0096 /// 0097 /// @param [in] position local 2D position 0098 Vector2 getField(const Vector2& position) const; 0099 0100 /// @copydoc MagneticFieldProvider::makeCache(const MagneticFieldContext&) const 0101 MagneticFieldProvider::Cache makeCache( 0102 const MagneticFieldContext& mctx) const override; 0103 0104 /// @brief Get the B field at a position 0105 /// 0106 /// @param position The position to query at 0107 Vector3 getField(const Vector3& position) const; 0108 0109 /// @copydoc MagneticFieldProvider::getField(const Vector3&,MagneticFieldProvider::Cache&) const 0110 Result<Vector3> getField(const Vector3& position, 0111 MagneticFieldProvider::Cache& cache) const override; 0112 0113 private: 0114 Config m_cfg; 0115 double m_scale; 0116 double m_dz; 0117 double m_R2; 0118 0119 Vector2 multiCoilField(const Vector2& pos, double scale) const; 0120 0121 Vector2 singleCoilField(const Vector2& pos, double scale) const; 0122 0123 double B_r(const Vector2& pos, double scale) const; 0124 0125 double B_z(const Vector2& pos, double scale) const; 0126 0127 double k2(double r, double z) const; 0128 }; 0129 0130 } // namespace Acts
| [ Source navigation ] | [ Diff markup ] | [ Identifier search ] | [ general search ] |
|
This page was automatically generated by the 2.3.7 LXR engine. The LXR team |
|