Conceptual design of the JT-60SA cryogenic system

Abstract

Abstract. The superconducting tokamak JT-60 Super Advanced (JT-60SA) is part of the Broader Approach Programme agreed between Europe and Japan. Among other in kind contributions, CEA is in charge of supplying the Cryogenic System which includes a Warm Compression Station, the Refrigerator Cold Box, the Auxiliary Cold Box, a compressed air station and the vacuum systems. The cryogenic system requires a refrigeration capacity of about 8 kW equivalent at 4.5 K. It will supply cryopump panels at 3.7 K, superconducting magnets and cold structures at 4.4 K, HTS current leads at 50 K, and thermal shields between 80 K and 100 K. The contract for design, manufacture, installation and commissioning was signed between CEA and Air Liquide Advanced Technologies (AL-AT) in November 2012. The Cryogenic System shall be operational in 2016. The paper presents the main technical requirements and the limit of supply, the description of the process proposed by AL-AT, the main components, the preliminary layout and the interfaces at the JT-60SA Naka site.

Parametric study and optimization of the cryo-magnetic system for EU DEMO at the pre-conceptual design phase

“…The optimization algorithm has been applied to the three TF winding pack designs, in order to identify for each TF design, the optimized set of parameters (∆𝑷, 𝑻 𝒊𝒏, 𝑪𝑰𝑪𝑪 ), which will minimize the input power of an ideal refrigerator at 300 K, with the given constraint on the temperature margin of 1.5 K with respect to the current sharing temperature. Another interesting result is the comparison with the reference parameters defined as (∆𝑷=1 bar, 𝑻 𝒊𝒏, 𝑪𝑰𝑪𝑪 =4.5 K), which are the commonly used conductor design parameters for ITER and for JT-60SA conductors [20]. The comparisons will allow to quantify the impact of the cooling requirement (∆𝑷, 𝑻 𝒊𝒏, 𝑪𝑰𝑪𝑪 ), between the refrigeration powers (enthalpy balance) Prefr, reference and Prefr, optimized, depending on the conductor designs.…”

Recent progress of the JT-60SA project

“…A huge cryogenic system procured by the EU has been newly constructed in the Naka site. It is composed of six gaseous helium storage vessels, eight warm compressors, four helium compressors, a refrigerator cold box (RCB) to produce helium at cryogenic temperatures, an auxiliary cold box (ACB) to distribute the cryogenic flows, and so on, as shown in figure 16 [39]. The ACB and RCB were delivered to the Naka site in April 2015 and the helium storage vessels in May 2015.…”

JT-60SA superconducting magnet system

“…The cryogenic system with an equivalent capacity of about 9 kW at 4.5 K provides refrigeration by supercritical helium at 4.4 K for the superconducting coils and structures, 50 K for HTS current leads and 80 K helium for thermal shields in addition to supercritical helium at 3.7 K for cryopumps [14] (figure 11). The special feature is the handling of the large heat load variations coming from coils (mainly CS) (with total heat loads on coils varying from 2 kW up to 7 kW) during the plasma operation and DWELL (cool down phase between a sequence of the plasma operation state).…”