Introduction

With four decades of experience and a worldwide installation base, Janis Research Company is a recognized leader in the design and manufacture of He-3 ultra low temperature systems. Operating down to less than 300 mK, these state of the art systems feature integrated designs for the He-3 insert with our high efficiency optical & non-optical cryostats. They are also supplied for any existing research or storage dewar, to extend the temperature capability of such set ups to the lowest achievable temperature with a He-3 insert. Janis Research’s approach maintains flexibility over the specification and integration of the He-3 cryostat with optional superconducting magnets, electronic components, temperature controllers and cryostats. We are thus able to offer systems with performance characteristics tailored to individual experimental, and budgetary requirements.

Janis’ staff of physicists and engineers has extensive experience in the design and operation of ultra-low temperature systems and is uniquely qualified to assist you with every step of your system purchase, from experimental design through post-installation support. All systems are fully integrated and liquid helium tested at our Wilmington, Massachusetts facility with installation, start-up and training available as needed.

The basic principle of a He-3 cryostat is to condense He-3 gas by bringing it in contact with a pumped He-4 reservoir (1 K pot). Low temperatures below 300 mK are then generated by reducing the vapor pressure on top of the liquid He-3 reservoir with either an internal (sorption) or an external pumping system. This may be done in a continuous flow mode or in a single shot mode. Continuous flow operating systems are generally more costly and require customized designs that are highly application dependent. If such a system is needed, please feel free to contact us and discuss these systems with our ultra low temperature physicists and engineers. These pages highlight the various standardized types of long term operating single shot systems with very quick regeneration times.

Single shot type He-3 cryostats typically include an internal sorption pump (SP), which offers very high pumping speeds for reducing the pressure on top of the He-3 reservoir, without requiring any costly external sealed pumps. This charcoal SP is integrated within the He-3 insert and its pumping speed controlled by controlling its temperature between approximately 4 K and 40 K. A specific amount of He-3 gas is supplied with each system, and is either permanently stored inside the insert (sample in vacuum), or externally stored in a separate volume (sample in liquid He-3). This gas is condensed at the 1 K pot with the SP off, then its temperature is decreased by turning the SP on. The He-3 reservoir is then quickly cooled down below 300 mK, depending on the configuration and intrinsic heat load of the experiment. The cooling power of these systems is also dependent on the type of system (sample in vacuum, exchange gas or LHe-3), and on other required features such as windows or other external variables dictated by the specific experiment.

When defining the system that is best suited for a specific application, one can concentrate on the following choices:

1. Sample loading: Standard loading, top loading or bottom loading
2. Sample location: High/ultra high vacuum, He-3 exchange gas, or LHe-3
3. Dewar type: Research type or storage helium dewar
4. Vacuum can seal: Indium wire or taper seal

Specific designs have also been developed for a variety of optical and non-optical experiments. These include a very wide range of applications such as Quantum Hall Effect, X-ray and Neutron studies, de Haas van Alphen measurements, material surface studies requiring cooling of Scanning Probe, Near Field Optical and Atomic Force Microscopes.

The standard models offered by Janis are listed below, and described in more detail in the following pages. Janis Research also offers a wide variety of customized systems that are tailored to highly specialized experiments. Please feel free to contact us to discuss your specific requirement with our expert cryogenic physicists and engineers, if it does not fit under any of the listed types or categories.

• Model HE-3-SSV: Standard loading - sample in vacuum
• Model HE-3-SVSD: Standard loading - sample in vacuum for storage dewar
• Model HE-3-SSXGAS: Standard loading - sample in exchange gas
• Model HE-3-SOSV: Standard loading, optical - sample in vacuum
• Model HE-3-SOSV-S: Standard loading, optical - sample in vacuum for FTIR experiments
• Model HE-3-SVC: Standard loading, compact - sample in vacuum
• Model HE-3-CCR-SSV: Standard loading - sample in vacuum - cryogen-free
• Model HE-3-SSV-CF: Standard loading - sample in vacuum - continuous flow
• Model HE-3-TLSL: Top loading - sample in liquid
• Model HE-3-TLOSL: Top loading, optical - sample in liquid
• Model HE-3-TLSV: Top loading - sample in vacuum

Special He-3 Cryostats

• Model HE-3-TLSL-NMR: Top loading - sample in liquid for NMR experiments
• Model HE-3-TLSUHV-SPM: Top loading - sample in UHV for Scanning Microscope Probe system
• Model HE-3-SSUHV-SPM/ESR: Standard loading - sample in UHV for Scanning Microscope Probe and Electron Spin Resonance systems
• Model HE-3-BLSUHV-STM: Bottom loading - sample in UHV for Scanning Tunneling Microscope system

He-3 System Comparison

A chart comparison of Janis Research's line of He-3 cryostats is available to download.  Please click on the link below.  The downloaded file will be in PDF format which is viewable and printable with Acrobat Reader, a free plug-in utility from Adobe.

To download the free acrobat plug-in software click here.

• He-3 System Comparison

Table of Contents

Pages

Standard He-3 Cryostats

Special He-3 Cryostats