High heat flux testing capabilities at Sandia National Laboratories - New Mexico Page: 2 of 8
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to Digital Library by the UNT Libraries Government Documents Department.
The following text was automatically extracted from the image on this page using optical character recognition software:
range of conditions: flow rates up to 30 l/s, pressures as high
as 7 MPa, and inlet temperatures up to 280 *C to simulate
those available in fusion devices. The EBTS is also equipped
with a closed helium coolant loop for testing of helium-
cooled components and heat exchangers. A fully equipped
computer laboratory is also housed at the PMTF for analytical
and experimental support of high-heat flux experiments.
The EBTS is a multi-purpose device for studying the
surface modification, thermal response and failure modes of
high heat flux materials and components. Figure 1 presents a
schematic of the EBTS showing a few of the diagnostics.
Table I lists the operating specifications of the EBTS, while
Table 2 describes the available diagnostics for HHF testing.
IR Camera /
N Sample Stage
94 cm '
FIGURE 1. EBTS SCHEMATIC
TABLE 1. EBTS OPERATING PARAMETERS
Beam Power 30 kW
Accelerating Voltage 30 kV
Beam Current 1 ampere
Target Area 0.1 to 100 cm2
Pulse length from 2 ms to continuous
TABLE 2. EBTS DIAGNOSTICS
Pyrometers (2) Surface temperatures
Infrared Camera & Video Surface temperature
Thermocouples (16) Bulk temperatures
Strain gauges Bulk response
Residual Gas Analyzer Partial pressures
Water calorimetry heat removal capability
Bore scope In situ surface
TV monitoring system Visual records
The 30 kW, heated-cathode, electron gun is mounted in a
stationary vertical position over the sample area. A hinged
door at the end of the 0.6 m diameter, I m long EBTS vacuum
vessel provides easy access for sample installation. Targets
of all shapes varying in size up to 30 cm x 60 cm can be
tested. A background pressure of 6 x 104 Pa is maintained
with a cold-trapped diffusion pump. A large variety of ports
and vacuum feedthroughs are available for diagnostics and
The electron source is equipped with a tungsten or tantalum
filament, and its maximum operating voltage is 30 kV
producing 30 kW of electron beam power. The uncorrected
beam at the target plane has a full-width-at-half-maximum
diameter of 5 mm for the tungsten filament and 3 x 3 mm2 for
the tantalum filament. A magnetic lens and deflection yoke
are used to focus, position and raster (up to 10 kHz in two
orthogonal directions) the electron beam to cover a variety of
sample surfaces with a finely tuned or defocused beam. The
temporal and spatial current profile from the rastered electron
beam is determined by a deep faraday cup equipped with
secondary electron suppression, and the energy deposition is
measured with a calorimeter or with water calorimetry of
actively cooled samples.
Various scenarios can be simulated with the electron gun,
since it provides a variable directed heat source. In the
standard, steady state operating mode, which utilizes a
tungsten filament, a 100 ms to continuous shot length over a
heated area from 1 to 100 cm2 is possible. In this operational
mode, the EBTS has been used to create a variety of high heat
flux tests from 25 kW/cm2 deposited on I cm2 for 100 ms to
10 W/cm2 deposited on a 100 cm2 area for over 900 s. The
system can also produce high power density, short pulse
length energy deposition. No raster is used in this mode.
Peak power densities up to 200 kW/cm2 over areas of
approximately 10 mm2 for times as short as 2 ms have been
There are five broad categories that high heat flux research
in the EBTS can be divided in to. These include:
1) Thermal Shock experiments which are intended to
subject many small test specimens to a systematic sequence
of identical intense energy depositions so that limiting
factors such as melting, cracking, delamination, and
outgassing can be compared among materials.
2) Thermal Response tests which expose miniature mock-
ups of complete high heat flux components to normal and off-
normal thermal conditions to verify the overall design
concept. This type of experiment is comprehensive in that
material selection, thermal hydraulic design, and the
robustness of the design are tested before the components are
manufactured and installed in a fusion device.
3) Thermal fatigue experiments which are used to examine
material failure and degradation due to repetitive thermal
cycling. Typically, high heat flux components are subjected
to hundreds up to thousands of energy depositions that are
representative in power density and duration to that expected
in a fusion device. Fatigue crack growth and/or interfacial
failure have proven to be common concerns.
4) Critical heat flux - burnout experiments which,are
designed to determine the heat transfer coefficients and
critical heat flux values for actively cooled components. The
use of thermocouple arrays to determine the contact resistance
across the interface between two dissimilar materials and the
Here’s what’s next.
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Youchison, D.L.; McDonald, J.M. & Wold, L.S. High heat flux testing capabilities at Sandia National Laboratories - New Mexico, article, December 31, 1994; Albuquerque, New Mexico. (digital.library.unt.edu/ark:/67531/metadc622331/m1/2/: accessed February 19, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.