Abstract

The first Lower Hybrid (LH) experiments were carried out with a Passive-Active Multijunction (PAM) launcher in H-mode plasmas. The experiments were performed on the HL-2A tokamak with the new 3.7 GHz LHCD system, installed and tested by SWIP in collaboration with CEA/RFM. The ELMs and local gas impact on LH power coupling was studied in the experiments. The coupled LH power in HL-2A was 200-500kW at large gap at the first experiments and reaches 900 kW now in H-mode, while it reaches 1MW in L-mode. The LH experiments on HL-2A show that the PAM launcher is a viable concept for high performance scenarios. The LH power can be coupled at large plasma-launcher gap, and assist in triggering and sustaining H-modes. Finally, an overview of the RF heating systems for the tokamak HL-2M is given. HL-2M will dispose of a 4 MW LH system and a 8 MW ECRH system, both of which are currently under installation at SWIP.

Highlights

  • Lower hybrid current drive (LHCD) is a well known method of non-inductive current drive in tokamaks, which has been used successfully in tokamaks around the world since the early 1980s

  • As a part of the 3.7 GHz LHCD system constructed on HL-2A tokamak, the third passive-active multijunction (PAM) launcher is developed and applied, making it possible to carry out Lower Hybrid (LH) experiments in H-mode plasmas by PAM antenna

  • A new 3.7 GHz LHCD system was developed and applied on HL-2A, in which a new passive-active multijunction (PAM) launcher was successfully used in H-mode experiments for the first time

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Summary

Introduction

Lower hybrid current drive (LHCD) is a well known method of non-inductive current drive in tokamaks, which has been used successfully in tokamaks around the world since the early 1980s. A PAM launcher was designed and constructed for Tore Supra [6], demonstrating long pulse operation at high coupled power (2.7 MW, 80 s) and ITER-relevant power density [7]. The PAM experiments in FTU and Tore Supra have shown excellent results of power handling and coupling at large plasma-launcher distances, making it an attractive launcher design for. This has so far only been demonstrated in L-mode plasmas. As a part of the 3.7 GHz LHCD system constructed on HL-2A tokamak, the third PAM launcher is developed and applied, making it possible to carry out LH experiments in H-mode plasmas by PAM antenna. Eight transmission lines (~ 20 m each) connect the klystrons to the launcher

Wave source
Transmission lines
Coupling effect on ELMs
Coupling effect on local gas puffing
Coupling optimization
ELMs mitigation by LH power
ECRH system
Findings
Summary and conclusions
Full Text
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