Ion temperature and toroidal rotation in JET's low torque plasmas

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Spectroscopy

Background:

• Accurate measurement of plasma properties like ion temperature (T_i) and toroidal velocity (v_ϕ) is crucial for fusion energy development.
• Charge-Exchange Recombination Spectroscopy (CXRS) is a key diagnostic tool, but challenges arise in low-impurity plasmas.
• Low signal and Doppler shifts in intrinsic rotation experiments at the Joint European Torus (JET) complicate T_i and v_ϕ determination.

Purpose of the Study:

• To develop and validate an optimal procedure for reliable T_i and v_ϕ estimation using CXRS data.
• To address the difficulties posed by low signal and Doppler shifts in intrinsic rotation experiments.
• To improve the accuracy of plasma diagnostics in fusion devices like JET.

Main Methods:

• Implementation of a beam modulation technique to enhance photon statistics.
• Application of CXRS with specific adaptations for low-impurity, carbon-wall fusion plasmas.
• Careful consideration and mitigation of errors from absolute calibration and magnetohydrodynamics (MHD) effects.

Main Results:

• A robust procedure for accurate and reliable estimation of T_i and v_ϕ from CXRS data has been established.
• The developed method effectively overcomes challenges associated with low signal and Doppler shifts.
• Minimization of errors related to calibration and MHD influences ensures data integrity.

Conclusions:

• The presented CXRS procedure offers a significant advancement in plasma diagnostic capabilities.
• This method provides reliable measurements essential for understanding and controlling fusion plasma behavior.
• The findings contribute to the ongoing efforts in achieving controlled nuclear fusion.