At the beginning of a machine operation, an assessment of the intrinsic error fields, spurious magnetic field perturbations which can affect plasma dynamics, is often carried out by executing the compass scan method [Scoville J.T. et al. Nucl. Fusion 43 250 (2003)]. This method relies on the application of 3D magnetic fields with various phases, induced by EF correction coils, to trigger a locked mode. The instant of locked mode onset allows the identification of the amplitude and phase of the intrinsic error field, from which the empirical correction currents for its minimization can be deduced. The presence of a locked mode needs to be carefully monitored during this study because of the potential disruptive mode behavior, especially in devices which can tolerate a maximum number of disruptions, as in SPARC and in ITER. A novel method, the so-called non-disruptive compass scan method [Paz-Soldan C. et al., Nuclear Fusion 54 (2014) 073013], avoids the disruption risk, as the name recalls, via magnetic island healing, i.e. stabilizing the locked mode. The magnetic island healing is achieved by switching off the error field correction coil current during the execution of the compass scan and asynchronously by increasing the plasma density. The crucial point of this new method is the detection of the locked mode to initiate the EFCC-density control actions. In this work, the locked mode detector adopted during non-disruptive compass scan test at JET is presented, together with brand-new locked mode metrics, which take into account the actual poloidal deformation due to a locked mode and a class of MHD instabilities, named Beta Alfve & PRIME;n Eigenmodes, that appear in the Mirnov signal in concomitance to the locked mode. The use of multiple metrics for locked mode detection during the execution of the non-disruptive compass scan increases the fidelity of the real-time control system to pinpoint the event, compensating possible magnetic probe failure, and initiate the control sequences to heal the magnetic island.

MARTe is a framework for real-time control that has been used in several fusion experiments. Re-cently, a new version named MARTe2 has been developed adhering to software quality standards.The framework supervises data movement and component interaction in real-time and is based onconfiguration information specifying the involved threads, the computation and the data manage-ment components. MDSplus is a data system widely adopted in the fusion community. MDS plus provides fast data acquisition and access to pulse files and is intended to provide a complete interfaceboth for the configuration of the experiment and the experimental results.MDSplus and MARTe2 are already integrated via a set of components that are able to (1) store adata stream originated in real-time in the pulse file, (2) get experiment set-up information, such asreference waveforms, from the pulse file to be used afterwards in real-time, (3) synchronize MARTe2components with other MDSplus components via MDSplus events. Even though the use of the abovethree components covers all the needed requirement for the integration of fast control and data ac-quisition, further integration is desirable. In particular, the configuration of MARTe2 applicationsis based on a very flexible set of components, either specified in a configuration file, or created onthe fly by a supervisory application. Adhering to the MDSplus design pattern that states that allthe configuration information should be specified inside the pulse file template, called ExperimentModel, it is possible to store configuration information in the experiment model together with theother experiment configuration parameters in order to let a given pulse file fully describe the associated experiment, including its configuration. A better integration is proposed here, that is, usingthe Device abstraction provided by MDSplus to specify the components involved in the data acqui-sition process and MDSplus expressions to specify data relationships, in order to describe also thereal-time components and the associated data flow. Following this approach, the whole real-time configuration would be described exactly as the rest of the other non real-time data acquisition com-ponents. All the required MARTe2 configuration information would be exposed to users via theconfiguration fields of the associated MDSplus devices, for which graphical interfaces can be readilydeveloped using the MDSplus Java Beans framework. Once the real-time components and the asso-ciated data flow have been described in the MDSplus experiment model, the corresponding MARTe2 configuration will be generated on the fly, integrating all the required consistency checks. Besides exposing to users a much less complicated and more intuitive configuration interface, theproposed approach minimizes the possible errors that could arise from a manual specification of theMARTe2 configuration that, when expressed via a text file, can be composed of thousands of lines fora non trivial configuration. A use case involving EQUINOX equilibrium computation in a MARTe2application, currently used in simulation, but adaptable for real-time control will be presented todemonstrate the feasibility and the advantages of the proposed approach.