First results with 3-strap ICRF antennas in ASDEX Upgrade

Abstract

Abstract. The 3-strap antennas in ASDEX Upgrade allow ICRF operation with low tungsten (W) content in the confined plasma with W-coated antenna limiters. With the 3-strap antenna configuration, the local W impurity source at the antenna is drastically reduced and the core W concentration is similar to the boron coated 2-strap antenna at a given ICRF power. Operation of the 3-strap antennas with the power ratio between the central and the outer straps of 1.5:1 and 2:1 is adopted to minimize the ICRF-specific W release.

Development of slow and fast wave coupling and heating from the C-Stellarator to NSTX

“…Extensive efforts have been and are underway to quantify the near field and far field effects, and efforts are also underway to modify antenna designs to reduce these fields. Particularly noteworthy recent antenna advances include the field aligned antenna on C-mod [25] and the 3-strap antenna on ASDEX Upgrade [26]. …”

Analysis of the ASDEX Upgrade 3-strap antenna with TOPICA code: Curved vs. flat 3D geometry

“…As already mentioned, before the 2015/2016 experimental campaign, the AUG 2-strap ICRF antennas with tungsten-coated limiters were replaced by 3-strap antennas, whose main goal was to reduce the release of tungsten in order to improve the ICRF operation [1]. Most of the 3-strap antenna design was actually performed with a simplified 3D flat model with the help of HFSS suite [4] and TOPICA; Figure 1 reports the TOPICA version of the 3D flat launcher.…”

“…Before the 2015/2016 experimental campaign, the ASDEX Upgrade (AUG) 2-strap ICRF antennas with tungsten-coated limiters were replaced by 3-strap antennas. The main goal of the 3-strap launcher was to reduce the release of tungsten (W) in order to improve the ICRF operation, which appeared to be troublesome after the all-W wall installation [1]. In this paper, we analyse the behaviour of the 3-strap antenna with the help of TOPICA code [2], a numerical tool able to take into account a realistic antenna geometry and an accurate plasma description.…”

Major upgrades of the high frequency B-dot probe diagnostic suite on ASDEX Upgrade

“…Examples of tokamaks using ICRF systems are ASDEX Upgrade [1], Alcator C-Mod [2], Tore Supra/WEST [3], and JET [4]. ITER, the next generation tokamak [5], and DEMO, the first generation fusion power plant [6], are also going to rely on ICRF power for their operation.…”

“…ITER, the next generation tokamak [5], and DEMO, the first generation fusion power plant [6], are also going to rely on ICRF power for their operation. The ICRF system on ASDEX Upgrade is tasked with studying ICRF power coupling and mitigating unwanted plasmamaterial interactions, while maintaining high performance core plasma [1,7]. In order to assist with this task, a number of probes have been installed that directly detect the ICRF waves' magnetic field components and their properties.…”