Angle-Resolved Photoemission Spectroscopy (ARPES) is used to study the electronic structure of the surface of solids. The ARPES technique employs a synchrotron or laser beam to interact with a sample, resulting in emission of photoelectrons.
通过分析光电子的能量和动量，可以映射材料的费米表面。ARPES实验通常在2开Kelvin - 10开Kelvin范围内进行，但是最近的研究趋势通常需要低于1 Kelvin（SUB-K）的温度。
Janis Research delivered the world’s first continuous operating high cooling power “wet” He-3 ARPES cryostat in 2008, achieving a base temperature of 0.9 K. Similar systems have since been installed at leading research facilities around the world, but the recent global helium shortage has made continuous operation of these large sub-K ARPES systems costly. In response to researcher demand, Janis Research has successfully developed another world first, a continuously operating high cooling power cryogen-free (“dry”) sub-K cryostat for ARPES. This dry He-3 system eliminates the need (and cost) of liquid helium, while also simplifying the design and dramatically reducing the cryostat size.
Cryostat design
Janis Research Dry Sub-K Arpes低温恒温器设计和制造为真正的UHV操作，可以烘烤至90C。一个两阶段的脉冲管冰箱（PTR）将两个内部平台和热屏蔽冷却至35 K（第一阶段）和3 K（第二阶段）。PTR由金属密封的CF法兰安装到Z-Motion线性翻译阶段。在真空烘烤期间，PTR升高并从低温恒温器中脱离，然后将其放到正常运行中。安装在PTR上的热交换器和平台上的predool两个独立的循环He-4和He-3气体的独立闭环。可以使用两个独立的He-3冷凝器将He-3气体转化为液体。冷凝器的选择取决于实验要求，并且是通过阀调节进行的。He-3锅用于收集冷凝的液体，He-3锅中的挖掘孔用于样品安装。热屏蔽中精确排列的插槽使同步加速器辐射或激光可以到达样品。可移动百叶窗也安装在热盾牌上，并将机械连接在一起。可以同时打开两个快门，以使用摇摆棒进行样品安装和去除，然后关闭以提高热性能。 A multifunction mechanical heat switch is used to precool the system, and to operate the system in variable temperature (He-4) mode. A large capacity gas sealed roots pump is used to circulate the He-3 gas.
Sliding sample access shutter
Operating principal
The system can be operated in three distinct modes.
He-4 Mode:In this mode, only He-4 gas is circulated; He-3 circulation is not required. After being precooled through the heat exchangers, He-4 gas is condensed through an impedance and enters a 1 K pot. Pumping on the He-4 gas results in a base temperature of ~1.3 K. The mechanical heat switch is configured to provide a direct thermal link between the 1K pot and the He-3 pot, resulting in variable temperature operation in the range of ~4 K – 320 K. This operating mode is especially user friendly, and offers fast thermal cycling of samples over a wide temperature range.
1 K操作模式：在此模式下，机械加热开关打开。外部阀门配置为将循环的HE-3气体通过1 K锅内的热交换器引导。He-3气体被预冷，然后在通过阻抗中膨胀后凝结，在HE-3锅中收集并将其冷却至500 mk。
JT operation mode:在此模式下，打开机械热开关，并配置了外部阀门将循环的HE-3气体引导到JTCU。HE-3排气流将传入的气体预冷至〜2 K，然后通过阻抗膨胀，将HE-3锅冷却至550 mk。
概括
The Janis Research dry sub-K cryostat for ARPES is a convenient multi-functional tool, suitable for a wide range of research applications. The system offers researchers the means to achieve sub-K temperatures in ARPES configuration, temperatures as low as 300 mK with beam slits closed, as well as high cooling power and unlimited experimental duration.
来源：https://www.janis.com