Description
Tokamak GOLEM serves as an educational tokamak at the Czech Technical University in Prague. It is the world's oldest operational tokamak. Its unique remote-control interface enables hands-on training for students not only at CTU, but also internationally. This contribution presents the latest students' projects on the tokamak GOLEM. This is the second part of two contributions on this subject.
Plasma current stabilization has been achieved using an auxiliary primary winding powered by AE TECHRON current amplifiers. Stabilization has been implemented for both chamber and plasma current using a user-defined waveform that has been manually set prior to each discharge.
A flattop plasma current was heuristically obtained and prolonged up to 10 ms through position stabilization and newly installed current stabilization systems. Work continues on analytical and numerical determination of stabilization waveforms for more robust flattop regimes.
The project covering direct control of the tokamak by a Bayesian optimizer was extended to include scaling factors for feed-forward waveforms for position and current control power supply which allowed to improve previous results.
A simple Arduino-based physical control panel is being constructed to automatically produce the discharge command in order to simplify setting up the GOLEM discharge so even the youngest visitors can run this under supervision.
Localized runaway electron (RE) losses are investigated using the DDRE (Direct Detection of Runaway Electrons) probe, which enables direct, energy and pitch-angle–resolved detection of runaway electrons via a cascade of thin scintillation pins. The results are compared with reconstructions of RE loss parameters derived from an inversion of a forward bremsstrahlung model and multi-view hard X-ray (HXR) measurements outside the vacuum vessel.
Correlations between HXR bursts and magnetohydrodynamic (MHD) activity were investigated by combining measurements from the Timepix3 pixel detector with Mirnov coil magnetic signals. Phase-coupled harmonic components with characteristic phase shifts were identified using continuous wavelet transform–based ridge extraction and minimum-coherence measures.
Ongoing research on the GOLEM tokamak investigates correlations between neural network–based visible camera tomography and Mirnov coil measurements.