Speaker
Dr
Nicolai Martovetsky
(LLNL)
Description
The Central Solenoid stack consists of 6 modules, 2.1 m tall each. In order to verify good impregnation, we performed a VPI (vacuum-pressure impregnation) test of a full cross section of the CS module, 14 conductors wide and 40 conductors tall. It was discovered that after preparation of the full cross section stack till completion of the VPI the stack shrunk in height by 20-25 mm. Our study of the literature and discussions with the leading experts in VPI did not reveal obvious reasons for this change of height. We launched a study to address this issue.
We assembled two 12x1 arrays and several 7x1 arrays in order to study characteristics of the dry winding pack under compressive force and effects of different fabrication steps. Then we impregnated these arrays in different conditions under compressive force and studied change of height as a result of compression, impregnation, gelling and curing of the stack of insulated conductors. We showed that by controlling the application of the compressive force, before closing the mold and during impregnation, one can reduce the height uncertainty. The most of the height reduction takes place while the glass is dry under the dead weight and the applied compressive force. Reduction of height during injection of the resin and during gelling, curing and cooling of the coil is noticeable, reproducible and relatively small. The paper presents results of our studies and recommendations for assembly and VPI of tall windings.
Author
Dr
Nicolai Martovetsky
(LLNL)
Co-authors
Dr
David Irick
(University of Tennessee Knoxville)
Erica Salazar
(General Atomics)
Haefelfinger Rolf
(General Atomics)
Dr
Richard Reed
(Composite Materials Inc)
