TA Instruments DSC Q Series, Руководство по началу работы

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DSC Q Series Getting Started Guide
14
DSC System Components
A functional DSC system has three major components: the instrument itself, which contains the system
electronics; the cell, which monitors differential heat flow and temperature; and a cooling accessory. The cooling
accessory selected depends on the temperature range desired for your experiments.
DSC Cell
In a "heat flux" DSC, the sample material, encapsulated in a pan, and
an empty reference pan sit on a thermoelectric disk surrounded by a
furnace. As the temperature of the furnace is changed (usually by
heating at a linear rate), heat is transferred to the sample and reference
through the thermoelectric disk. The differential heat flow to the sample
and reference is measured by area thermocouples using the thermal
equivalent of Ohm's Law.
This simple relationship, however, does not take into account extraneous heat flow within the sensor or between
the sensor and sample pan. The TA Instruments Q Series DSC's are specifically designed to account for those
latter heat flows.
The cell sensor consists of a constantan body with separate raised platforms to hold the sample and reference.
The platforms are connected to the heating block (base) by thin-walled tubes that create thermal resistances
between the platforms and the base. Area detectors (thermocouples) on the underside of each platform measure
the temperature of the sample and reference. A third thermocouple measures the temperature at the base. The
equation below shows the thermal network model which represents this cell arrangement, and the resultant
heat flow expression that describes this cell arrangement (designated the To [Tzero
TM
] cell) is
The first term in this expression is the equivalent of the conventional single-term DSC heat flow expression. The
second and third terms account for differences between the sample and reference resistances and capacitances