Environment Chambers

As many materials may change compositional, structurally, and/or spectrally when exposed to different planetary surface conditions, C-TAPE has devoted efforts to the construction of environment chambers that allow samples to be exposed to different types of planetary surface environments along with the capability to measure reflectance
spectra of samples in situ. To date, the focus has been on developing chambers that simulate current Mars surface conditions. To this end, we have constructed two Mars Environment (ME) chambers.

1. Mini-ME and Big-ME,
2. Multipath cell (“the coffin”),
3. Vacuum ovens,
4. Glove boxes,
5. Parr bombs.

1. Mini-ME and Big-ME

	The smaller chamber (Mini-ME) can accommodate samples up to 40 mm in diameter and 10 mm in thickness. Sample cooling is provided by a cooling tube that is in thermal contact with the sample(s) in the chamber.
	The larger chamber (Big-ME) measures 90 60 x 60 cm and is equipped with viewing ports allowing unobstructed viewing of any part of the chamber. Sample cooling will be provided by a “race track” type cooling system allowing simultaneous multi-sample cooling.

Both Big-ME and mini-ME are fitted with 50 mm diameter window holders for spectral acquisition while the samples are held in the controlled environment. Available window materials include sapphire, polycarbonate, and zinc selenide. Collectively these windows provide high transparency (>99%) from 0.2 to ~16 microns and selective transmission at longer wavelength intervals.

2. Multipath cell (“the coffin”)

C-TAPE has a Neoplas Control Q-Macs Multipass cell that can be interfaced with the Bruker Vertex 70 FTIR spectrometer (fitting into the sample compartment). It provides an adjustable path length ranging from 3 to 36 m. A series of aluminum mirrors and KBr windows allow the incident light beam to enter the cell, which is a sealed chamber with purging abilities and can have up to 24 reflections along the length of the cell before being directed to the detector. This capability is intended for transmission measurements of suspended dust and aerosols.

3. Vacuum ovens

The laboratory is equipped with three vacuum ovens that can be used for sample synthesis or to subject samples to low atmospheric pressure ± variable atmospheric compositions ± elevated temperatures to assess factors such as mineral stability.

VBF-1200X-H8 One of the vacuum ovens, the VBF-1200X-H8, is a 30 segment programmable instrument capable of attaining temperatures up to 1200°C under various gas atmospheres. Water-cooled stainless steel vacuum flanges with valves are employed to achieve vacuum pressures of 10-2 - 10-5 torr through a mechanical or molecular vacuum pump. Samples are housed in the horizontal quartz tube chamber which measures 19 cm ID x 34 cm.
EQ-DZF-6020-HT500P A second oven, the EQDZF-6020-HT500P, is a 30 segment programmable vacuum oven capable of obtaining temperatures up to 500°C under various gas atmospheres. The 30 X 30 X 28 cm chamber is constructed of stainless steel (1Cr18Ni9Ti) and uses a water-cooled silicone door gasket as a vacuum seal and can achieve pressures down to 2 torr.
VWR 1410 The third oven, the VWR 1410, is a vacuum oven capable of obtaining temperatures up to 250°C under various gas atmospheres. The 20.5 X 22 X 27.5 cm chamber is constructed of stainless steel and uses a silicone door gasket. Modifications have been made to the unit to enable operation of an internally installed deuterium UV light source while the chamber is under vacuum but not being heated.

4. Glove boxes

C-TAPE facilities include both a single-user glove box (815-PGB, Plas-Labs) and a dual user glove box (818-GBB, Plas-Labs) ideal for working in tandem, and large enough to house many of our instruments to manipulate and acquire data for air-sensitive materials. Both chambers have electrical pass-throughs to power the equipment inside, an evacuable transfer chamber, and ground key cock valves to allow the introduction of gas and purging. The interior of the single-user glove box measures 80 X 65 X 55 cm, whereas the larger dual-user glove box has inner dimensions of 152 X 97 X 79 cm.

5. Parr bombs

C-TAPE has a number of Parr Acid Digestion bombs (model 4749) that can subject samples to pressures of 124 bar at temperatures up to 250°C to examine high-pressure ± temperature sample alteration. The Parr bombs are lined with Teflon inserts to minimize sample interactions with the pressure vessel.