ST40 data and control

Highlights: • An R₀ = 0.4 m spherical tokamak, ST40, was built and operated by Tokamak Energy Ltd. • A modular Machine Control System was developed to tackle plant complexity. • Plasma Control System, operating at 10 kHz, was developed in MATLAB/Simulink. • MDSplus is used for data storage, and for passing data across systems and platforms. -- Abstract: The first operational phase of ST40, a new R₀ = 0.4 m high field spherical tokamak, took place in early 2018. Its results are presented in [1]. During these first operations, the device was run in a reduced configuration, but all the main components of control and data flow were already in place. ST40 operations are controlled by two systems: Machine Control System (MCS) and Plasma Control System (PCS). MCS is responsible for the 24/7 monitoring and control of the ST40 plant, whereas PCS controls the tokamak during a pulse using feedforward and feedback controllers. All the acquired data is stored in an MDSplus database.