IEEE TRANSACTIONS ON PLASMA SCIENCE 1 XSC Tools: a software suite for tokamak plasmas shape control design and validation Gianmaria De Tommasi, Member, IEEE, Raffaele Albanese, Giuseppe Ambrosino, Marco Ariola, Senior Member, IEEE, Massiliamo Mattei, Senior Member, IEEE, Alfredo Pironti, Filippo Sartori, Fabio Villone and JET-EFDA Contributors Abstract— This paper describes a set of graphic tools for the design and validation of the new plasma shape controller (eXtreme Shape Controller, XSC), recently implemented at the JET tokamak. The XSC enables operation with high elongation and high triangularity plasmas. The software suite, called XSC Tools, has been developed to automate the design procedure of the XSC. These tools make use of GUIs to allow nonspecialist users to prepare new operative scenarios, without the help from modeling and control specialists. Once a new controller is generated all its parameters are saved into a text file, which is used to perform the validation of the scenario via simulations. The same file is then loaded by the real-time code running on the plant, without any further processing. This feature guarantees that the controller which is running on the plant is exactly the same one validated through simulations. An additional effort has been made in order to make the XSC Tools machine independent, i.e. to enable their use on different tokamaks. Index Terms— Software tools, Control systems validation, Tokamaks control. I. INTRODUCTION Tokamaks [1] are the most promising confinement devices in the field of thermonuclear fusion. Recently, many exper- iments in operating tokamaks and, as a consequence, a lot of effort in the research on tokamak control, have focused on the so-called advanced tokamak scenarios (AT, [2], [3], [4]). An advanced tokamak plasma can be defined as a plasma where the following conditions are simultaneously obtained: stationary state; a high plasma kinetic pressure; a large fraction of self-driven current; a sufficiently good particle and energy confinement. AT scenarios are aimed at allowing steady-state operation without the need to drive a large amount of plasma current by external non-inductive drive systems, thus making it more efficient. In this context several problems need to be adequately resolved to achieve these simultaneously plasma performance R. Albanese, G. Ambrosino, G. De Tommasi and A. Pironti are with Associazione Euratom-ENEA-CREATE, Universit` a di Napoli Federico II, via Claudio 21, 80125, Napoli, Italy {raffaele.albanese,ambrosin,detommas,pironti}@unina.it. M. Ariola is with Associazione Euratom-ENEA-CREATE, Universit` a di Napoli Parthenope, via Medina 40, 80133 Napoli, Italy ariola@uniparthenope.it. M. Mattei is with Associazione Euratom-ENEA-CREATE, Universit` a Mediterranea di Reggio Calabria, Loc. Feo di Vito, 89060, Reggio Calabria, Italy mattei@ing.unirc.it. F. Sartori is with Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3EA, UK fisa@jet.uk. F. Villone is with Associazione Euratom-ENEA-CREATE, Universit` a di Cassino, via Di Biasio 43, 03043, Cassino, Italy villone@unicas.it. [5], [6], thus the role of automatic control is becoming more and more significant. New control systems should be designed in order to achieve the requirements for an economically attractive steady-state fusion power plant. In particular the plasma shape control system plays an essential role, since an accurate plasma boundary control is needed to obtain the vertical elongated plasmas with high triangularity required in AT scenarios. Triangularity and elon- gation describe how far the plasma cross section is from a circle. These extreme shapes allow to achieve high values of β , which is the plasma kinetic energy to magnetic energy ratio, and thus to increase both plasma density and confinement time [7]. Other important reasons to precisely control the plasma shape are the optimization of the coupling with the additional heating systems, the avoidance of wall interactions, the diver- tor shape optimization for pumping. In order to achieve and maintain extreme shapes, the feed- back controller needs to regulate many different points all around the plasma boundary. This task is complicated by the fact that plasma shapes characterized by a large elongation makes even the vertical stabilization difficult to guarantee in the presence of unexpected large disturbances, such as for instance like edge-localized modes (ELMs). To control the plasma shape with the needed accuracy the boundary is usually described by plasma-wall distances, called gaps, by the locations of the strike points on the divertor tiles, and the position of the X-point (see Figure 1). Therefore a model-based multi-input-multi-output (MIMO) approach is needed to design the shape controller, in order to achieve the high performance request. H ∞ approach [8] has been successfully validated on TCV tokamak to control at the same time the plasma current, vertical position and some plasma boundary descriptors [9], [10]. In [11] authors propose a solution adopted on DIII-D which emphasizes the X-point control accuracy over the shape accuracy. A general discussion on the design of plasma position, current and shape controllers, including the choice of the controlled variables, can be found in [12]. To effectively control extremely shaped plasmas the entire boundary needs to be specified, i.e. a large number of geo- metrical descriptors need to be controlled. The eXtreme Shape Controller (XSC, [13]) has been de- veloped to control the whole plasma boundary controlling up to 32 geometrical descriptors (gaps plus strike points and X-