Energy flux to the ASDEX-Upgrade diverter plates determined by thermography and calorimetry

Abstract

A new thermography system with high time resolution was put into operation at ASDEX-Upgrade and is routinely used to determine the energy flux onto the lower diverter plates. The measurements allow the power deposition to be chamcterized during dynamic events such as ELMS and disruptions, as well as the asymmetry of the inboardloutboard power load. A power balance is set up even during single discharges and the losses are found to be fairly equal to the power input.

Particle, heat, and sheath power transmission factor profiles during ELM suppression experiments on DIII-D

“…The tile edges are very carefully aligned and edge heating effects have been greatly reduced but are still visible. The 2D heat transfer code, also used at TEXTOR [10] to convert IR camera surface temperature to heat flux, is the THEODOR code [11] with no surface layer. The outer strike point is a region of net erosion so deposited layers would not be an issue for these measurements.…”

Far scrape-off layer particle and heat fluxes in high density – High power scenarios

“…The power onto the divertor target is detected by an infra-red (4.7 µm) line camera with ∼ 3.8 kHz frame rate. The heat flux is derived using the Theodor code [17].…”

Divertor IR thermography on Alcator C-Mod

“…We also assume that the camerabody/lens/periscope system emits as a graybody. Thus the detected signal, S, is parameterized as S(T surf .T body , τ int )=Offset(τ int )+α(τ int )B(T body )+ β(τ int )B(T surf ) (1) where B(T) is the blackbody emission 9 within the spectral bandpass of the camera for a temperature T, α is a constant times τ int , (determined by varying T body while viewing a cold plate), and β is a calibration parameter (also linear in τ int ) that depends on the viewed surface emissivity, the periscope transmission, the detector sensitivity, and the angle with which the surface is viewed. It can be different for each pixel and is determined as described in Section III.…”

“…IR thermography is an important tool that can quantify heat-flux "footprints" at divertor targets [1][2][3][4][5] . On ITER, IR thermography is to be used as the primary diagnostic for a number of important measurements, including…”