| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 272155 | Fusion Engineering and Design | 2012 | 6 Pages |
One of the primary challenges of auxiliary heating of tokamaks in the ion cyclotron range of frequencies (ICRF) is the reduction of impurities associated with ICRF operation. On Alcator C-Mod, a new magnetic field-aligned antenna was optimized for magnetic flux coupling, power handling, and minimized integrated parallel electric field (E∥). Initial simulations performed using both slab and cylindrical geometry suggested nearly complete cancellation of E∥ in front of the antenna structure for certain toroidal phasings. Using toroidal models, the cancellation of E∥ is more modest, suggesting 3-D geometrical effects are important. Using finite element method simulations with a 3-D toroidal cold plasma model, multiple antenna phases were analyzed: [0, π, 0, π], [0, 0, π, π], [0, π, π, 0], [0, 0, 0, 0], [0, π/6, 0, π/6], and [0, π/2, π, 3π/2]. In each case, the field-aligned antenna had reduced integrated E∥ relative to the existing non-aligned antenna geometry, with the greatest reduction for monopole [0, 0, 0, 0] phasing.
► First comparison of magnetic field-aligned ICRF antenna with horizontal ICRF antenna using 3-D finite element cold plasma model. ► Simulations suggest a reduction of the integrated parallel electric field for all toroidal phasings for a field-aligned antenna compared with a conventional antenna. ► The largest reduction in the RF potential occurs for monopole phasing, which has the largest RF potential contribution for conventional ICRF antennas.
