Sample Environment of the POWGEN Instrument

Powder Diffractometer

POWGEN | BL-11A | SNS

Sample Environment of the POWGEN Instrument

Sample Holders

Various sample holders are used for the sample environment equipment mentioned below. For photos and detailed information about materials and dimensions, please refer to the document Powgen sample cans.

Powgen Automatic Changer

The Powgen Automatic Changer (PAC) is the second generation sample changer that was developed for Powgen. The changer has a carousel that holds a maximum of 24 sample-filled vanadium cans, and data may be collected in a temperature range of 20 to 300 K. The cool down time from room temperature to 20 K is 30 minutes. The sample may be changed at 20 K, which takes about 20 minutes.

Vacuum Furnace / Gas Insert

A traditional vacuum furnace built with vanadium heating elements is available for high-temperature measurements from room temperature to 1200°C. Cooling to 100°C takes approximately 4 hours. The vacuum level of the furnace is ~2 x 10^-5 torr. The aluminum tail of the furnace has been modified with vanadium windows for the primary beam. Installing a niobium heating element increases the maximum temperature to 1600ºC; however, Q coverage is limited due to the Nb peaks observed in the back- and forward-scattering detectors.

This furnace can also be configured to have a quartz insert that allows flow of various gas mixtures through the sample using the gas handling system. Approved gases include H2, CH4, CO, CO2, N2, Ar, He and O2. The sample is loaded in a quartz basket with frit at the bottom and quartz wool on top to allow flow of gas through the sample. The furnace is capable of heating up to 850°C with this insert.

Orange Cryostat

The orange cryostat is a standard 50 mm bore cryostat with modified tails similar to the vacuum furnace to eliminate aluminum in the path of the primary neutron beam. The temperature range is 2 to 300 K.

Cryofurnace (JANIS)

The Janis cryofurnace is a top loading CCR with two different stick setups. The cold stick has a temperature range of 5 to 500 K, while the hot stick can go from 30 to 750 K.

Slim Sam (5T Magnet)

Slim Sam is a 5T vertical magnet with a cryo-stick that can go down to 2K. However, this has aluminum in the path of the primary beam and hence has substantial Al peaks. Users are strongly encouraged to discuss with instrument staff before requesting the magnet for their proposals.