Impact of window temperature variations on ITER toroidal interferometer and polarimeter (TIP) measurements

Conference · Fri Oct 31 04:00:00 EDT 2025

DOI:https://doi.org/10.1088/1361-6587/ae1411· OSTI ID:3001674

Akiyama, T; Zeeland, M A Van; Finkenthal, D K; LeSher, M; Finden, R; Trost, P; Gattuso, A; Miranda, S; Groh, M; de Looz, Marc-André ^[1]; Watts, C

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1. Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Abstract The toroidal interferometer and polarimeter (TIP) is one of the primary electron density diagnostics on ITER. To meet measurement requirements over several thousand seconds, environmental factors such as changes in the window temperature, air temperature, and humidity, which can cause uncompensated phase drifts, must be minimized. This paper reports measurements of the phase shift induced by ZnSe and BaF₂ windows as their temperature is varied utilizing the TIP prototype. To accomplish these measurements, test pieces of BaF₂ and ZnSe are placed in a small oven that is located in one leg of the 10.59/5.22 micron two-color interferometer TIP prototype. The oven temperature was varied from room temperature to ∼90 °C, which is slightly higher than the expected window temperatures on ITER. The vibration compensated phase shifts measured for these two materials are dϕᵥ꜀ /dT/L = 0.0121 and −0.275 deg. /°C/cm −1 for BaF₂ and ZnSe, respectively. From these measurements, it was concluded that temperature variations of the environmental/secondary confinement barrier window and primary vacuum window have to be suppressed within approximately 1°C and 2°C, respectively, in order to passively meet the electron density measurement requirements in ITER.

• Research Organization: Princeton Plasma Physics Laboratory; General Atomics, San Diego, CA (United States)
• Sponsoring Organization: DOE Laboratories; United States Government; DOE; ITER Organization; Savannah River National Lab; Princeton Plasma Physics Laboratory; Oak Ridge National Laboratory; ITER
• DOE Contract Number: AC02-09CH11466
• OSTI ID: 3001674
• Country of Publication: United States
• Language: English