Quantum Design CM-C, Руководство пользователя

Страница: 11 / 54

Quantum Design VSM Oven Option User’s Manual, Rev. A3
1-1
May 2011
C H A P T E R 1
Introduction to the VSM Oven Option
1.1 Introduction
This chapter contains the following information:
○
Section 1.2 is an overview of the VSM
Oven option.
○
Section 1.5 outlines safety considerations
for working with the VSM Oven option.
○
Section 1.3 describes notable features
of the VSM Oven option.
○
Section 1.6 lists contact information at
Quantum Design and its service centers.
○
Section 1.4 describes the VSM Oven
option theory of operation.
1.2 Overview
The Oven for the VSM provides a way to make sensitive D.C. magnetometry measurements at
controlled temperatures from 300 K up to 1000 K. Using a specially designed heated sample
holder and VSM sample rod with electrical feedthrough, the VSM Oven vibrates the sample
inside the VSM detection coilset. Both the standard VSM option and a high-vacuum option are
required in order to operate the VSM Oven.
Heating of the sample is achieved by applying current to a Platinum resistive heating element
lithographically patterned onto the custom-designed sample holder. A thermocouple embedded
on the back side of the sample holder measures the temperature in the sample region, and a
thermistor at the top connector of the sample holder corrects for heating of the cold junction. In
this manual, we will refer to the VSM Oven sample holder as the
heater stick
(see Figure 5-1). To
maximize thermal contact, the sample is attached to the heater stick using alumina-based cement
(included in VSM Oven Option User’s Kit, Figure 5-5). Then, the platinum heater region is
wrapped securely with a thin copper-foil radiation shield that retains heat and reduces thermal
gradients between the sample and heater stick.
The VSM Oven heater region is a 1 inch long heated substrate on which the sample is glued. This
design is in contrast to that of other high-temperature oven inserts for magnetometers, which
often are bulky and have long thermalization times. By embedding the thermometry in the
substrate along with the heater, we have made vast improvements on typical thermal-response
times and sample-temperature accuracy. Due to the low thermal mass of the heated substrate, you
can maintain heating rates at the sample of over +200 K/min throughout the full temperature
range of the oven. Note that the cooling rate will depend on the current temperature of the heater
stick, because cooling occurs through thermal radiation from the heater stick to the VSM
detection coilset.