A new 3MW ECRH system at 105 GHz for WEST

The aim of the WEST experiments is to master long plasma pulses (1000s) and expose ITER-like tungsten wall to deposited heat fluxes up to 10 MW/m$^2$. To increase the margin to reach the H-Mode and to control W-impurities in the plasma, the installation of an upgraded ECRH heating system, with a gyrotron performance of 1MW/1000s per unit, is planned in 2023. With the modifications of Tore Supra to WEST, simulations at a magnetic field B$_0$∼3.7T and a central density n$_{e0}$∼6 × 10$^{19}$ m$^{−3}$ show that the optimal frequency for central absorption is 105 GHz. For this purpose, a 105 GHz/1MW gyrotron (TH1511) has been designed at KIT in 2021, based on the technological design of the 140 GHz/1.5 MW (TH1507U) gyrotron for W7-X. Currently, three units are under fabrication at THALES. In the first phase of the project, some of the previous Tore Supra Electron Cyclotron (EC) system components will be re-installed and re-used whenever possible. This paper describes the studies performed to adapt the new ECRH system to 105 GHz and the status of the modifications necessary to re-start the system with a challenging schedule

Subtype-specific actions of β-amyloid peptides on recombinant human neuronal nicotinic acetylcholine receptors (α7, α4β2, α3β4) expressed in Xenopus laevis oocytes

1. Two-electrode voltage-clamp electrophysiology has been used to study the actions of two amyloid peptides (Aβ(1–42), Aβ(1–40)) on α7, α4β2 and α3β4 recombinant human neuronal nicotinic acetylcholine receptors (nicotinic AChRs), heterologously expressed in Xenopus laevis oocytes. 2. The application of Aβ(1–42) or Aβ(1–40) (1 pM–100 nM) for 5 s does not directly activate expressed human α7, α4β2 or α3β4 nicotinic AChRs. 3. Aβ(1–42) and Aβ(1–40) are antagonists of α7 nicotinic AChRs. For example, 10 nM Aβ(1–42) and Aβ(1–40) both reduced the peak amplitude of currents recorded (3 mM ACh) to 48±5 and 45±10% (respectively) of control currents recorded in the absence of peptide. In both the cases the effect is sustained throughout a 30 min peptide application and is poorly reversible. 4. Aβ(1–42) and Aβ(1–40) (10 nM) enhance currents recorded in response to ACh (3 mM) from oocytes expressing α4β2 nicotinic AChRs by 195±40 and 195±41% respectively. This effect is transient, reaching a peak after 3 min and returning to control values after a 24 min application of 10 nM Aβ(1–42). We observe an enhancement of 157±22% of control ACh-evoked current amplitude in response to 100 nM Aβ(1–42) recorded from oocytes expressing α4β2 nicotinic AChRs. 5. Aβ(1–42) and Aβ(1–40) (10 nM) were without antagonist actions on the responses of α3β4 nicotinic AChRs to ACh (1 nM–3 mM)

Development and Application of 3.7GHz LHCD system on HL-2A and Development of RF Heating system on HL-2M

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

Development and Application of 3.7GHz LHCD system on HL-2A and Development of RF Heating system on HL-2M

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