Solidification Using a Baffle in Sealed Ampoules

Short Name: SUBSA

Facility Description

The Solidification Using a Baffle in Sealed Ampoules (SUBSA) facility objective is to advance understanding of the processes involved in semiconductor crystal growth. SUBSA offers a gradient freeze furnace for materials science investigations that can reach 850 °C. Samples are contained in transparent quartz or ceramic ampoules with high-definition video imaging available in real time, along with remote commanding of thermal control parameters.

SUBSA operates within the Microgravity Sciences Glovebox (MSG) facility for containment, utilities provision, remote commanding, and video imaging capabilities. It was originally operated successfully onboard ISS Flight UF2 in 2002 during the MSG rack’s first mission increment. SUBSA was refurbished and updated for reflight with modernized software, data acquisition, high-definition video, and communication interfaces to the ISS and MSG facility. In 2020, SUBSA was refurbished again and updated for reflight.

The SUBSA furnace operates in an ambient air environment and can process 16-mm diameter cylindrical ampoules up to 290 mm in length. Samples are typically melted at a controlled rate, held at maximum temperature to stabilize, and then solidified at a precise cooling rate in gradient freeze mode. The furnace hot zone is a 20-cm length stainless steel tube having an actively heated portion of 10 cm. There is an adjacent transparent zone of 9.5 cm length in which the solid-liquid interface is formed and observed. The sample cartridge head acts as a cold side thermal sink to the MSG facility’s cold plate, which is held at a nominal temperature of 22 °C.

Thermal parameters can be adjusted based on real-time video imaging for maximum benefit to the science team. The behavior of the solid-liquid interface is observed and recorded in real time using a video system that offers remotely controlled zoom, fine focus, image setting adjustments, and selectable frame rate. Four thermocouple sensor channels are available for measuring sample thermal profiles at a user-defined frequency rate, along with optional overlay of science data onto the video feed. Precision heating and cooling control supports up to eight process segments, including various combinations of dwell, heat-up, or cool-down periods with resolution and stability of 0.1 °C on the setpoints and 0.1 °C/hr on the ramp rates. Individual process segments can also be adjusted while within that segment.

Availability: Please contact the facility manager

ISS Environment: Internal

Owner: NASA

Operator/Implementation Partner:
Redwire Space

Developer(s):
NASA Marshall Space Flight Center; Techshot, Inc. (now Redwire Space)

Facility Manager:
Rachel Ormsby
Redwire Space

Manager Email:
rachel.ormsby@redwirespace.com

Parent Facility: MSG

Child Facility:

Sponsoring Space Agency: NASA

Equipment Category: Capability

Additional Information:

SUBSA on NASA’s SSRE

Solidification Using a Baffle in Sealed Ampoules
iss058e028142 (3/7/2019) --- View of the Microgravity Sciences Glovebox (MSG) during configuration of the SUBSA (Solidification Using Baffles in Sealed Ampoules) hardware in the MSG Work Volume in the Destiny Laboratory aboard the International Space Staion(ISS). SUBSA is a high-temperature furnace that can be used to study how microgravity affects the synthesis of semiconductor and scintillator crystals. Image courtesy of NASA.