Inductively driven transients in the CS Insert Coil (I): Heater calibration and conductor stability tests and analysis

Abstract

The CS Insert Coil (CSIC), a well-instrumented 140 m long NbsSn solenoid wound onein-hand and installed in the bore of the CS Model Coil, was tested during the summer of 2000 at JAERI Naka, Japan, within the framework of the International Thermonuclear Experimental Reactor large projects [1]. The maximum transport current in the CSIC was 40 kA and the peak background field was 13 T. The coils were cooled by forced flow Hel nominally at 4.5 K and 0.6 MPa. An inductive heater was used to study stability and quench propagation in the CSIC. In this first of two companion papers we concentrate on the conductor stability tests, while a second paper is dedicated to the analysis of quench propagation [2]. The stability margin of the conductor was measured for different transport currents, helium mass flow rates and temperature margins, and the corresponding results will be presented and discussed. In the analysis, a major uncertainty comes from the assessment of the actual energy input and its partition between jacket and cable. Therefore, an electromagnetic model of the inductive heater was developed and validated. Using this input, the stability margin is computed with the Mithrandir code and compared with experimental results, showing good agreement.

Analysis and interpretation of the full set (2000–2002) of TCS tests in conductor 1A of the ITER Central Solenoid Model Coil

“…Mithrandir was originally developed to overcome the shortcomings of previous models where the same thermodynamic state was assumed for the helium in the central channel and in the cable bundle region of the dual-channel CICC typical of all ITER conductors. Mithrandir was validated against stability, quench and heat slug propagation data from the QUELL experiment and, more recently, against stability, quench and AC loss data of the ITER CSI coil [26][27][28] and against quench data of the ITER TFI coil [29].…”

Inductively driven transients in the CS Insert Coil (II): Quench tests and analysis

“…An inductive heater was used to test stability and quench of the CSIC. In this second of two companion papers we concentrate on the analysis of quench initiation and propagation, based on the study of heater calibration and conductor stability presented in the first paper [2]. The initiation and propagation of an inductively driven quench was tested here for the first time in a two-channel Nb 3 Sn conductor, for different transport currents, delay times of the dump, and temperature margins, and a selection of the corresponding results will be presented and discussed.…”

Analysis of Quench Propagation in the ITER Poloidal Field Conductor Insert (PFCI)

“…Phase 1 should actually require a detailed electro-magnetic/ thermal-hydraulic model of the IH, as used e.g., in [6], but this is beyond the scope of the present paper. Here we parametrically studied several different space distributions of the above-mentioned 85% in the jacket (the time distribution was always assumed to be a square wave of duration ), then following the diffusion of the heat through the jacket with a one-dimensional (radial) heat conduction model, assuming as boundary condition the jacket temperature distribution computed by Mithrandir/M3 along the length of the IH.…”

“…Unfortunately none of these coefficients is known very well, so they are typically used as parameters to be chosen within a reasonable range by suitable parametric study. Here we use [6], and . The fourth heat transfer coefficient typically needed by 1-D code is that between central channel and cable bundle region,…”

“…The 1-D Mithrandir code [5], already validated against stability and quench data from previous Nb3Sn Insert Coils [6]- [8] as well as against quench data from ITER sub-size conductors [9], and the quasi-3D M3 code [10], implementing a more detailed thermal-hydraulic description of the CICC cross section, are used here to analyse the issues of quench propagation in the PFCI.…”