Geodesic acoustic modes (GAMs) have been investigated in JET ohmic discharges using mainly Doppler backscattering. Characteristics and scaling properties of the GAM are studied. Time and spatial resolved measurements of the perpendicular velocity indicate that GAMs are located in a narrow layer at the edge density gradient region with amplitude...
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August 27, 2020 (v1)PublicationUploaded on: December 4, 2022
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August 26, 2020 (v1)Publication
Abstract A dimensionless collisionality scan in low-triangularity plasmas in the Joint European Torus with the ITER-like wall (JET-ILW) has been performed. The increase of the normalized energy confinement (defined as the ratio between thermal energy confinement and Bohm confinement time) with decreasing collisionality is observed. Moreover, at...
Uploaded on: March 1, 2023 -
August 26, 2020 (v1)Publication
A method for obtaining an accurate wavelength calibration over the entire focal plane of the JET edge CXS spectrometers is presented that uses a combination of the fringe pattern created with a Fabry–Pérot etalon and a neon lamp for cross calibration. The accuracy achieved is 0.03 Å, which is the same range of uncertainty as when neglecting...
Uploaded on: December 4, 2022 -
July 31, 2020 (v1)Publication
New techniques that attempt to more fully exploit spectroscopic diagnostics in the divertor and pedestal region during highly dissipative scenarios are demonstrated using experimental results from recent low-Z seeding experiments on Alcator C-Mod, JET and ASDEX Upgrade. To exhaust power at high parallel heat flux, q ‖ > 1 GW/m 2 , while...
Uploaded on: December 4, 2022 -
July 14, 2020 (v1)Publication
The impact of the finite grid size in SOLPS-ITER edge plasma simulations is assessed for JET H-mode discharges with a metal wall. For a semi-horizontal divertor configuration it is shown that the separatrix density is at least 30% higher when a narrow scrape-off layer (SOL) grid width is chosen in SOLPS-ITER compared to the case for which the...
Uploaded on: March 27, 2023 -
July 31, 2020 (v1)Publication
A strong effect of divertor configuration on the threshold power for the L-H transition (P LH ) was observed in recent JET experiments in the new ITER-like Wall (ILW) [1–3] . Following a series of EDGE2D-EIRENE code simulations with Be impurity and drifts a possible mechanism for the P LH variation with the di- vertor geometry is proposed. Both...
Uploaded on: March 27, 2023 -
August 27, 2020 (v1)Publication
High spatial resolution Doppler backscattering measurements in JET have enabled new insights into the development of the edge Er. We observe fine-scale spatial structures in the edge Er well with a wave number krρi ≈ 0.4–0.8, consistent with stationary zonal flows, the characteristics of which vary with density. The zonal flow amplitude and...
Uploaded on: March 26, 2023