3HELIUM SYSTEMS
Introduction
With more than 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) or with a cryocooler. 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 provide much higher cooling power, but 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 (or the He-3 condenser in the cryogen-free He-3 system) 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 He-3 liquid
3. Dewar type: Research type or storage helium dewar
4. Vacuum can seal: Indium wire or taper seal
5. Pre-cooling: LHe-4 or cryocooler
6. Operation mode: Single shot or continuous flow
7. Options: Magnet, rotating sample holder, optical windows or fiber optics, sliding seal, wiring, coaxial cables, etc.
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.
Standard He-3 Cryostats
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-SSV-CCR2: 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.
He-3低温恒温器系统
经过四十余年的设计和安装经历，Janis公司现在已经成为He-3超低温系统设计和生产方面的领导者。He-3制冷系统通过He-3减压可以获得低于300mK的低温，这些最先进的系统把He-3插件与高效光学或非光学恒温器集成。这些组件也可以和客户现有的杜瓦相接合，把温度降至He-3系统能够实现的最低温度。Janis为He-3系统提供了各种灵活的选项如：超导磁体、电子组件、温度控制器等等。Janis可以根据用户的需要和预算提供He-3制冷系统。
Janis的物理学家和工程师在超低温系统的设计和使用上有着丰富的经验，可以对客户从购买、实验设计到售后后技术支持的每一步提供协助。所有系统在Wilmington，Massachusetts工厂集成，并经过液氦测试，同时可以提供安装、启动和培训。He-3制冷系统的基本原理是通过与泵抽的He-4杜瓦(1K Pot)接触冷凝He-3，然后通过内置吸附泵或外置泵降低He-3蒸汽压，从而把温度降至300mK以下。可以是连续流模式，也可以采用一次降温模式。连续流模式通常比较昂贵，根据客户需要定制。
单次降温模式He-3低温恒温器通常包括一个内置吸附泵，可提供高抽速降低He-3蒸汽压，从而省掉昂贵的外置密封泵。内置的炭吸附泵集成在He-3制冷系统内，可以把温度控制在4K和40K之间来控制抽速。一定量的He-3气体随系统提供给用户，或者永久存储于系统内，或者单独存放在一个容器中。He-3气体在1K冷凝 pot（吸附泵关着），然后打开吸附泵降低He-3蒸汽压从而降低温度。然后存放He-3的储槽会迅速降温至300mK以下，具体情况根据构造和负载而定。制冷能力也取决于系统（样品，交换气体或He-3）和其他因素如窗口和一些特定实验的变量。
定义一个系统是否符合具体的应用时，可以集中在以下几个指标和选项：
- 样品装载：标准装载，顶部安装或底部安装
- 样品环境：高/超高真空，He-3交换气体或液态He-3
- 杜瓦种类：研究型或存储型液氦杜瓦
- 真空密封：铟线或锥型密封
Janis提供以下标准型号的He-3低温系统：
- Model HE-3-SSV: 标准样品装载－样品在真空
- Model HE-3-SVSD: 标准样品装载－样品在真空－存储杜瓦
- Model HE-3-SSXGAS: 标准样品装载 －样品在交换气体中
- Model HE-3-XGHS: 超紧凑型交换气体处理系统
- Model HE-3-SOSV: 标准样品装载, 带光学窗口－样品在真空
- Model HE-3-SOSV-S: 标准样品装载, 带光学窗口－样品在真空用于FTIR 实验
- Model HE-3-SVC: 标准样品装载, 紧凑型－样品在真空
- Model HE-3-SSV-CCR: 标准样品安装－样品在真空－无制冷剂
- Model HE-3-SSV-CF: 标准样品安装－样品在真空–连续流
- Model HE-3-TLSL: 样品顶部安装－样品在液体
- Model HE-3-TLOSL: 样品顶部安装, 带光学窗口－样品在液体
- Model HE-3-TLSV: 样品顶部安装－样品在真空
特殊型号制冷机：
- Model HE-3-TLSL-NMR: 样品顶部安装 – 样品在液体中，用于核磁共振实验
- Model HE-3-TLSUHV-SPM: 样品顶部安装 -样品在超高真空中，用于扫描探针显微镜
- Model HE-3-SSUHV-SPM/ESR: 标准样品安装 -样品在超高真空中，用于扫描探针显微镜和电子自旋共振系统
- Model HE-3-BLSUHV-STM: 样品底部安装 -样品在超高真空中，用于隧道扫描显微镜
He-3系统结构图