VPF Series Cryostat Systems — Sample in Vacuum
Simple and inexpensive, VPF cryostats provide a variable temperature sample environment with no valves or adjustments required. Designed with versatility in mind, the VPF cryostat is field-upgradeable with additional feedthroughs, windows, or sample holders if experimental requirements change. Models for operation to 500 K, 700 K, or 800 K are available.
The Janis VPF cryostat is an inexpensive liquid nitrogen cryostat offering operating temperatures from 65 K to 800 K. Simple to use and refill, the VPF system uses a refill style displacer assembly and built-in heater to provide variable temperature capability. Temperatures below 77 K are achieved using an optional pumping manifold. High temperature capability is provided using special sensors and heaters.
Access to the sample compartment is provided by a quick disconnect clamp. Samples are mounted in a 3 in diameter vacuum space (2.5 in for VPF-800) and can be connected with cryogenic-service wiring (single conductor or coaxial). The four-way optical sample chamber (with a numeric aperture of 1.0) can be configured for reflectance or transmission measurements. Standard windows are fused natural quartz offering transmission from the UV to near-IR regions. Optional window materials can be installed to span the far/mid- IR, VUV, and x-ray regions for a variety of spectroscopic measurements. The refill assembly permits refilling of the LN2 reservoir without affecting the controlled temperature.
Typical applications for the VPF include spectroscopy (photoluminescence, FTIR, UV- visible), materials characterization (resistivity, Hall effect), as well as low- temperature imaging, microscopy, and component testing. Low cost, light weight, and portability make the VPF the ideal cryostat for multipurpose laboratories, demonstrations, and integration with existing instrumentation. VPF-100 and VPF-800 models are in stock for fast delivery to your site.
Custom configurations may be fabricated to fit restricted spaces (such as in a magnet system or spectrometer) or to allow the insertion of very large samples (such as semiconductor wafers or "cold plates" to cool several samples at once).
- Fused quartz windows
- 4-way optical access (f = 1.0)
- Si diode thermometer and heater (thermocouple for VPF-800)
- Electrical feedthrough for thermometry
- Optical sample holder
- Refill assembly for continuous operation
- Complete system test
- Complete selection of ancillary equipment including temperature controllers, pumping stations, and storage Dewars
- Electrical measurement packages (sample holders, wiring, and feedthroughs)
- Pumping manifold for <77 K operations (see Other configurations)
- Sample holder for DLTS (see fixed probe sample holder in Other configurations)
- Additional bottom warm window port and quartz window
- Special adaptor for use with SuperTran liquid helium transfer line (see Other configurations)
- Specially modified window block with large window as an option
VPF Series Specifications
|Initial cooldown time (to 77 K)||15 min|
|VPF-100, S, ST||65 to 500 K|
|VPF-700S, ST||65 to 700 K|
|VPF-800||65 to 800 K|
|LN2 hold time:|
|77 K||5 h; (VPF-100[T]: ~8 h)|
|100 K||4.5 h|
|200 K||2.5 h|
|Typical stability(2)||±50 mK|
|Vacuum level required(3)||10-4 Torr|
|Approximate weight||7 lb (3.3 kg)|
|(1)Temperatures <77 K with optional pumping manifold|
(2)Measured with temperature controller
(3)Vacuum pressure measured at room temperature prior to adding cryogens
Special adaptor allows VPF cryostat to be used with a SuperTran liquid helium transfer line
The VPF is normally a liquid nitrogen only cryostat. This special adaptor allows customers to run their existing VPF with liquid helium by connecting a standard inventory FHT-ST line to the fill port of the VPF cryostat. The base temperature is then extended to ~10 K. Purchasing an adaptor and a standard FHT-ST can be more cost effective than purchasing a complete ST-100 cryostat.
Special dual reservoir VPF system
This special dual reservoir VPF system with sample immersed in liquid nitrogen allows the user to freeze the liquid nitrogen in the outer reservoir to keep the inner reservoir from boiling. This prevents bubbles from forming in the sample area that could otherwise cause problems for optical measurements.
Standard window block with countersunk screw holes option
Janis Research usually uses pan-head screws on the retainers of window blocks, which add about 0.125 in to each side of the window block. In cases were space is an issue, talk to your sales engineer about countersunk screw holes in the retainers so that flathead screws can be used, as shown in this photo. This option can be offered on most window blocks with o-ring sealed windows. The window block shown can be used on our model VPF-100, VPF-800, ST-100, CCS-150, CCS-100/202 CCS-100/204, and SHI-4-2.
VPF-100 with special NW-25 and NW-40 flanges on the window ports
The VPF-100 shown has special NW-25 and NW-40 flanges on the window ports. This allows it to be connected to the vacuum space on a beam line with the same type of flanges. This can be done on any Janis system with o-ring sealed windows.
Modified window block
These photos show a standard optical cryostat with a specially modified window block. Two of the windows are our standard 1.63 in diameter clear view fused quartz. The other two windows are a special 2.63 in diameter clear view fused quartz. This window block can be used as an option on many other systems such as ST-100, VPF-100, SHI-4-2, SHI-4-5, SHI-4, CCS-150, CCS-450, CCS-100/202, and CCS-100/204. (The CCS-100/204 use an optional large window using a different window block.) Contact Janis for more information.