Synthetic fast ion diagnostics in tokamaks: comparing the Monte Carlo test particle code ASCOT against experiments

TL;DR

This paper evaluates the accuracy of the ASCOT Monte Carlo code in simulating fast ion diagnostics in tokamaks by comparing synthetic diagnostic outputs with experimental measurements from ASDEX Upgrade, DIII-D, and JET.

Contribution

It introduces and validates synthetic diagnostics in ASCOT against real tokamak measurements, enhancing confidence in simulation-based diagnostic testing.

Findings

Good agreement between synthetic and experimental data

Validation across multiple diagnostics and tokamaks

Supports use of ASCOT for predictive diagnostics

Abstract

Measuring fast ions, most notably fusion alphas, in ITER and future reactors remains an issue that still lacks an adequate solution. Numerical simulations are invaluable in testing the potential and limitations of various proposed diagnostics. However, the validity of the numerical tools first has to be checked against results from existing tokamaks. In this contribution, a variety of synthetic diagnostics for fast ions (collective Thomson scattering, neutral particle analyzer, neutron camera, infrared measurements, fast ion loss detector and activation probe) from the orbit-following Monte Carlo code ASCOT are compared to measurements from several tokamaks (ASDEX Upgrade, DIII-D and JET). Within the limitations of physics included in the numerical model and availability of input data from experiments, the agreement between synthetic data and measurements is found to be quite good.