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Title: Thermophysical properties of advanced carbon materials for Tokamak limiters

Technical Report ·
DOI:https://doi.org/10.2172/6188316· OSTI ID:6188316

A plasma limiter is used to control the plasma size in Tokamak fusion research devices and serves as the primary area of plasma wall interaction. Contact with the plasma produces very high heat fluxes, typically 500--5000 W/cm/sup 2/ for pulse lengths of 1--10 seconds. Wall temperatures can reach as high as 3000 K resulting in significant melting or wall erosion. Graphite and graphite composites have been chosen as the materials that best meet the requirements of this severe environment. Measurement of the thermophysical properties of these materials is critical to the modeling of the thermal response of the limiters during operation. The thermal diffusivities, thermal conductivities and thermal expansions of several candidate materials were measured. The categories of materials investigated in this study were pyrolytic graphite and annealed pyrolytic graphite; fine-grained graphites; anisotropic carbon/carbon fiber composites; two-directionally woven fibers with a graphitized pitch matrix; and carbon/carbon fiber composites with a four-directionally woven carbon fiber wave. The thermal conductivities of the carbon/carbon fiber composites were determined as a function of fiber orientation. Conductivities were measured using both the laser flash diffusivity technique and the thermal comparative method. The advantages and disadvantages of each of these methods are discussed and the data compared. In addition, thermal expansion was measured as a function of fiber orientation using pushrod dilatometry techniques. 34 refs., 50 figs., 5 tabs.

Research Organization:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
DOE Contract Number:
AC04-76DP00789
OSTI ID:
6188316
Report Number(s):
SAND-88-2057; ON: DE89012799
Resource Relation:
Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English