Experimental Apparatus for Measuring Ultralow Thermal Conductivity Structures
<p>Ultralow thermal conductivity materials play an important role in many applications such as space exploration and thermal insulation. One of the primary challenges in studying heat conduction in these materials is performing basic thermal conductivity measurements, because even a small a...
| Summary: | <p>Ultralow thermal conductivity materials play an important role in many
applications such as space exploration and thermal insulation. One of the primary
challenges in studying heat conduction in these materials is performing basic
thermal conductivity measurements, because even a small amount of steady heating
results in enormous temperature increases. While methods do exist to measure the
thermal conductivities of macroscopic materials, these techniques are difficult to
apply to the microscopic samples that are the only samples available for some
materials.</p>
<p>In this thesis, we describe an optical, non-contact experimental system for
measuring ultralow thermal conductivities. The system we designed and built is a
modified pump-and-probe system. With this system, we will be able to measure a
sample as small as tens of microns without having physical contact between the
tester and the sample. Different from a traditional pump-and-probe method, we
used a pump laser with a very low repetition rate of a few hundred Hz, which can
efficiently reduce the steady heating, and at the same time the transient heating is
still enough to give a measurement result.</p>
<p>In the following chapters, we will first discuss the background of this thesis,
including a brief introduction to the manufacture of the nano-lattice and the
principles of the pump-and-probe method. Then we will go through some
calculations done during the design process of the apparatus. Finally, we will
present the test results from the experiments and compare them against the
simulation.</p> |
|---|