141 research outputs found
TOPICA: a virtual prototyping suite for plasma facing antennas
No full textAn innovative tool has been realized for the simulation of 3-dimensional Ion Cyclotron Radio Frequency (ICRF) antennas in a realistic geometry and with an accurate plasma model. The approach to the problem is based on an integral-equation formulation for the self-consistent evaluation of the current distribution on antennas facing a plasma in a slab geometry. The plasma enters the formalism via a surface impedance matrix; for this reason any plasma model can be used (presently the FELICE code has been adopted). A vacuum-term extraction and an analytical evaluation of some integrals are employed that permit to significantly reduce the integration support and to obtain a high numerical efficiency leading to the practical possibility of using sub-domain basis functions on each conductor of the antenna system. Calculation of field distributions (both magnetic and electric), useful for sheath considerations, is included. This tool has been implemented in a suite that is modular and applicable to ICRF antenna structures of arbitrary shape. This new simulation tool can assist during the detailed design phase and for this reason can be referred to as a Virtual Prototyping Laboratory (VPL). The VPL has been tested against assessed codes and against measurements of mock-up and prototype antennas
New Capabilities of TOPICA Code: Lower Hybrid Antennas and Full Toroidal Plasmas
No full textTOPICA (TOrino Polytechnic Ion Cyclotron Antenna) code is a numerical suite aimed at the performance prediction and analysis of plasma-facing antennas. It is capable of handling real-life 3D antenna geometries (with housing, Faraday screen, etc.) as well as a realistic plasma model, including measured density and temperature profiles. Thanks to the approach underlying the code (i.e. the formal splitting of the problem into two parts: the vacuum region around the antenna and the plasma region inside the toroidal chamber), TOPICA can be extended to deal with lower hybrid (waveguide grill) antennas, as well as toroidal plasma. TOPICA has been upgraded to simulate and design lower hybrid (waveguide grill) antennas. On the other hand, to include plasma curvature effects, TOPICA can adopt the plasma impedance matrix computed independently via the fully toroidal TORIC plasma code. This way TOPICA both provides more accurate antenna parameters and yields the proper input (i.e. the electric field in front of the Faraday shield) to self-consistently run TORIC in a subsequent plasma analysis. In this work an account for the new capabilities of TOPICA will be presente
Prediction of plasma-facing ICRH antenna behavior via a Finite-Element solution of coupled Integral Equations
No full textThe demand for a predictive tool to help designing ICRH antennas for fusion experiments has driven the development of codes like ICANT, RANT3D, and the early developments and further upgrades of TOPICA code. Currently, TOPICA handles the actual geometry of ICRH antennas (with their housing, etc.) as well as a realistic plasma model, including density and temperature profiles and FLR effects. Both goals have been attained by formally splitting the problem into two parts: the vacuum region around the antenna, and the plasma region inside the toroidal chamber. Field continuity and boundary conditions allow writing a set of coupled integral equations for the unknown equivalent (current) sources; finite elements are used on a triangular‐cell mesh and a linear system is obtained on application of the weighted‐residual solution scheme. In the vacuum region calculations are done in the spatial domain, whereas in the plasma region a spectral (wavenumber) representation of fields and currents is adopted, thus allowing a description of the plasma by a surface impedance matrix. Thanks to this approach, any plasma model can be used in principle, and at present Brambilla’s FELICE code has been employed. The natural outputs of TOPICA are the induced currents on the conductors and the electric field in front of the plasma, whence the antenna circuit parameters (impedance/scattering matrices), the radiated power and the fields (at locations other than the chamber aperture) are then obtained. An accurate model of the feeding coaxial lines is also included. This paper is precisely devoted to the description of TOPICA, whereas examples of results for real‐life antennas are reported in a companion paper [1] in this proceedings
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