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Martovetsky, Nicolai N

Publications and source records attributed to Martovetsky, Nicolai N.

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Development of the bus joint for the ITER Central Solenoid

The terminations of the Central Solenoid (CS) modules are connected to the bus extensions by joints located outside the CS in the gap between the CS and Torodial Field (TF) assemblies. These joints have very strict space limitations. Low resistance is a common requirement for all ITER joints. In addition, the CS bus joints will experience and must be designed to withstand significant variation in the magnetic field of several tenths of a Tesla per second during initiation of plasma. The joint resistance is specified to be less than 4 nOhm. The joints also have to be soldered in the field and designed with the possibility to be installed and dismantled in order to allow cold testing in the cold test facility. We have developed coaxial joints that meet these requirements and have demonstrated the feasibility to fabricate and assemble them in the vertical configuration. We introduced a coupling cylinder with superconducting strands soldered to the surface of the cable that can be installed in the ITER assembly hall and at the Cold Test Facility. This cylinder serves as a transition area between the CS module and the bus extension. We made two racetrack samples and tested four bus joints in our Joint Test Apparatus. Resistance of the bus joints was measured by a decay method and by a microvoltmeter; the value of the current was measured by the Hall probes. This measurement method was verified in the previous tests. The resistance of the joints varied insignificantly from 1.5 to 2 nOhm. One of the challenges associated with a soldered joint is the inability to use corrosive chemicals that are difficult to clean. This paper describes our development work on cable preparation, chrome removal, compaction, soldering, and final assembly and presents the test results.

Martovetsky, Nicolai N↗
DOE OSTI2013

Qualification of the ITER CS Quench Detection System using Numerical Modeling

Abstract The ITER Central Solenoid (CS) magnet needs to be protected against overheating of the conductor in the event of the occurrence of a normal zone (NZ). Due to a large amount of stored energy and slow NZ propagation, the NZ needs to be detected and the switchyard needs to open the breakers within 2 s after detection of the NZ. The CS will be discharged on a dump resistor with a time constant of 7.5 s. During operation of the CS and its interaction with the poloidal field (PF) coils and plasma current, the CS experiences large inductive voltages from multiple sources, including nonlinear signals from eddy currents in the vacuum vessel and plasma current variation, that make the task of detecting the resistive signal even more difficult. This inductive voltage needs to be cancelled by quench detection (QD) hardware (e.g., bridges, converters, filters, processors) and appropriate processing of the QD signals to reliably detect NZ initiation and propagation. Two redundant schemes are proposed as the baseline for the CS QD System: 1) A scheme with Regular Voltage Taps (RVT) from triads of Double Pancakes (DP) supplemented by Central Difference Averaging (CDA) and by digital suppression of the inductive voltage from all active coils (the CS and PF coils). Voltage taps are taken from helium outlets at the CS outer diameter. 2)A scheme with Cowound Voltage Taps (CVT) taken from cowound wires routed from the helium inlet at the CS inner diameter. Summary of results of the numerical modeling of the performance of both baseline CS QD systems is presented in this paper. Index Terms Quench detection, Central Solenoid, ITER

Martovetsky, Nicolai N↗
DOE OSTI2012

Qualification of the Joints for ITER Central Solenoid

The ITER Central Solenoid has 36 interpancake joints, 12 bus joints, and 12 feeder joints in the magnet. The joints are required to have resistance below 4 nOhm at 45 kA at 4.5 K. The US ITER Project Office developed two different types of interpancake joints with some variations in details in order to find a better design, qualify the joints, and establish a fabrication process. We built and tested four samples of the sintered joints and two samples with butt-bonded joints (a total of eight joints). Both designs met the specifications. Results of the joint development, test results, and selection of the baseline design are presented and discussed in the paper.

Central Solenoid↗
DOE OSTI2011

Central Solenoid Insert Technical Specification

The US ITER Project Office (USIPO) is responsible for the ITER central solenoid (CS) contribution to the ITER project. The Central Solenoid Insert (CSI) project will allow ITER validation the appropriate lengths of the conductors to be used in the full-scale CS coils under relevant conditions. The ITER Program plans to build and test a CSI to verify the performance of the CS conductor. The CSI is a one-layer solenoid with an inner diameter of 1.48 m and a height of 4.45 m between electric terminal ends. The coil weight with the terminals is approximately 820 kg without insulation. The major goal of the CSI is to measure the temperature margin of the CS under the ITER direct current (DC) operating conditions, including determining sensitivity to load cycles. Performance of the joints, ramp rate sensitivity, and stability against thermal or electromagnetic disturbances, electrical insulation, losses, and instrumentation are addressed separately and therefore are not major goals in this project. However, losses and joint performance will be tested during the CSI testing campaign. The USIPO will build the CSI that will be tested at the Central Solenoid Model Coil (CSMC) Test Facility at the Japan Atomic Energy Agency (JAEA), Naka, Japan. The industrial vendors (the Suppliers) will report to the USIPO (the Company). All approvals to proceed will be issued by the Company, which in some cases, as specified in this document, will also require the approval of the ITER Organization. Responsibilities and obligations will be covered by respective contracts between the USIPO, called Company interchangeably, and the industrial Prime Contractors, called Suppliers. Different stages of work may be performed by more than one Prime Contractor, as described in this specification. Technical requirements of the contract between the Company and the Prime Contractor will be covered by the Fabrication Specifications developed by the Prime Contractor based on this document and approved by the Company and ITER. The Fabrication Specifications may reflect some national requirements and regulations that are not fully provided here. This document presents the ITER CSI specifications.

36 MATERIALS SCIENCE↗