CTS-spec

CTS-spec

Collective Thomson scattering (CTS) spectral density function calculation package for plasma diagnostics.

Overview

This package provides tools for calculating and analyzing collective Thomson scattering spectra in plasmas, including both electron plasma waves (EPW) and ion acoustic waves (IAW). It is particularly useful for plasma diagnostics in high-energy density physics experiments.

Features

• Calculation of CTS spectra for multi-component plasmas
• Support for both EPW and IAW components
• FLYCHK integration for ionization state calculations
• Distribution function calculations
• Spectrum convolution with instrument function
• Fitting utilities for experimental data analysis

Project Structure

CTS-spec/
├── src/
│   └── cts_spec/
│       ├── __init__.py
│       ├── core.py           # Core CTS calculation module
│       ├── distribution.py   # Distribution function calculations
│       ├── fitting.py        # Fitting utilities
│       ├── convolution.py    # Spectrum convolution functions
│       └── flychk.py         # FLYCHK functions
├── script/
│   ├── cts_plot_epw.py      # EPW spectrum plotting script
│   └── cts_plot_iaw.py      # IAW spectrum plotting script
├── test/                    # Test suite
│   ├── test_spectrum.py     # Spectrum comparison tests
│   ├── conftest.py          # Pytest configuration
│   └── README.md            # Test documentation
├── sample/
│   ├── epw/                 # Sample EPW data
│   │   ├── EPW-test_axis.txt
│   │   └── EPW-test_2.9ns.txt
│   └── iaw/                 # Sample IAW data
│       ├── IAW-test_axis.txt
│       └── IAW-test_2.9ns.txt
├── README.md
├── LICENSE
└── pyproject.toml           # Project configuration

Directory Descriptions

• src/cts_spec/: Core package source code
  • core.py: Main module containing CTS calculation functions
  • distribution.py: Distribution function calculations
  • fitting.py: Fitting utilities for experimental data
  • convolution.py: Spectrum convolution functions
• script/: Example scripts for different analysis scenarios
  • cts_plot_epw.py: Script for plotting EPW spectra
  • cts_plot_iaw.py: Script for plotting IAW spectra
• test/: Test suite for spectrum calculations
  • test_spectrum.py: Tests for spectrum comparison
  • conftest.py: Pytest configuration
  • README.md: Test documentation
• sample/: Sample data files for testing and examples
  • epw/: Sample EPW data files
  • iaw/: Sample IAW data files

Prerequisites

• Required
  • Python >= 3.11 (for tomllib support)
  • NumPy >= 1.20 (for improved type hints and array operations)
  • SciPy >= 1.7.0
  • Matplotlib >= 3.4.0
  • pytest (for testing)

Note: The code uses NumPy's type hints and array operations extensively. All numerical calculations are performed using floating-point numbers (64-bit precision).

Installation

From source

python3 -m pip install CTS_SPEC_ROOT_DIRECTORY

where CTS_SPEC_ROOT_DIRECTORY points to the directory including this README.md file.

Testing

The project includes a comprehensive test suite to ensure calculation consistency. See test/README.md for detailed testing information.

Quick Start

# Run all tests
pytest

# Run specific tests
pytest test/test_spectrum.py::TestSpectrumCalculations::test_epw_spectrum

Setting Up Reference Data

Before running tests, you need to set up the reference data:

# Create reference directories
mkdir -p sample/ref/epw sample/ref/iaw

# Copy current calculation results as reference data
cp sample/epw/EPW-calc_* sample/ref/epw/
cp sample/iaw/IAW-calc_* sample/ref/iaw/

Usage

Basic Example

import numpy as np
from cts_spec import cts_spec

# Define wavelength array
lmd_nm = np.linspace(526.0, 527.0, 1000)  # nm

# Define plasma parameters
# Electron parameters: [temperature (eV), density (1e18 cm^-3), velocity (km/s)]
param_ele = np.array([[100, 1.0, 0.0]])

# Ion parameters: [temperature (eV), density (1e18 cm^-3), velocity (km/s), 
#                 ionization state, ion mass]
param_ion = np.array([[1000, 1.0, 0.0, 10, 64]])

# Laser parameters: [wavelength (nm), scattering angle (deg), norm, offset]
par_laser = [526.5, 60, 1.0, 0.0]

# Calculate spectrum
spectrum = cts_spec(lmd_nm, param_ele, param_ion, par_laser)

Advanced Features

FLYCHK Integration

# Enable FLYCHK for ionization state calculation
spectrum = cts_spec(lmd_nm, param_ele, param_ion, par_laser, flychk=True)

Separate EPW and IAW Components

# Calculate only ion acoustic wave component
spectrum_iaw = cts_spec(lmd_nm, param_ele, param_ion, par_laser, 
                        separate=True, iaw=True)

# Calculate only electron plasma wave component
spectrum_epw = cts_spec(lmd_nm, param_ele, param_ion, par_laser, 
                        separate=True, iaw=False)

Distribution Functions

from cts_spec import dfe, dfi

# Calculate electron distribution function
v_ele = np.linspace(-1e8, 1e8, 1000)  # cm/s
f_ele = dfe(v_ele, param_ele[0, 0], param_ele[0, 2], param_ele[0, 1])

# Calculate ion distribution function
v_ion = np.linspace(-1e7, 1e7, 1000)  # cm/s
f_ion = dfi(v_ion, param_ion[0, 0], param_ion[0, 2], param_ion[0, 1], param_ion[0, 4])

Documentation

For detailed documentation of the API and usage examples, please refer to the docstrings in the source code.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the BSD 2-Clause License. See the LICENSE file for details.

Copyright

This code is written by Kentaro Sakai, modified by Yusuke Konishi, Tatsumi Aoyama, and Kazuyoshi Yoshimi.

Citation

If you use this software in your research, please cite:

@software{cts_spec,
  author = {Kentaro Sakai, Yusuke Konishi, Tatsumi Aoyama, and Kazuyoshi Yoshimi},
  title = {CTS-spec: Collective Thomson Scattering Spectral Density Function},
  year = {2026},
  url = {https://github.com/fusion-repo/CTS-spec}
}