HR: 0800h
AN: V31C-0605    [Abstracts]
TI: Rapid Quench Cold-Seal Apparatus with Computer-Controlled Pressure and Temperature Cycling
AU: * Johnston, A
EM: adjohn@uoregon.edu
AF: University of Oregon, Department of Geological Sciences, Eugene, OR 97403, United States
AU: Senkovich, D
EM: dsenko@uoregon.edu
AF: University of Oregon, Science Machine Shops, Eugene, OR 97403, United States
AB: We have constructed two computer-controlled, rapid quench, hydrothermal apparatuses that are ideal for experimentation on volcanological, geothermal, and ore deposit research problems. The devices can achieve maximum pressures of about 2 kbar and temperatures to 1100C, have the ability for experiments to be quenched very rapidly in a water-cooled environment, and are interfaced with computers which can control any regimen of pressure and/or temperature cycling that may be desired, accomplished via Lab-View software and data acquisition and motion control boards from National Instruments. The rapid quench aspects of the design were developed originally by Dr. Phil Ihinger and have subsequently been adopted by many labs around the world; a good summary description of these aspects of the equipment, and the use of filler-rods for controlling redox conditions in such equipment, are provided by Matthews et al. (2004, Am. Mineral., 88: 701-707). Our design has fixed Rene 41 pressure vessels, furnaces that are raised and lowered by computer controlled pneumatic cylinders and water cooling systems that are controlled by computer operated solenoid valves. The novel feature of our design is the pressure generation and control systems. We coupled the seal-ends of commercially available (HIP) pressure generators to shop-built linear actuators consisting of nearly frictionless ball lead screws within thick walled stainless steel housings. These in turn are driven by NEMA size 23 stepper motors coupled to 100:1 gear reduction units. The actuators require 21 revolutions to achieve their full stroke of 12.7 cm which displaces about 10 cc of fluid. Operating the motors at the relatively low resolution of 800 steps per revolution leads to about 132,000 steps per cm of travel of the pressure-generating piston, providing exceptionally high precision and excellent pressure control. Instantaneous decompression can be achieved by simply opening a valve while motor-controlled decompression from 2 kbar to 1 bar can occur over time spans ranging from about one minute to months. This equipment will find immediate use in studies of decompression- induced magmatic vesiculation and crystallization in sub-volcanic and volcanic conduit environments and decompression-induced precipitation of fracture-filling ore and silicate minerals in crustal hydrothermal environments.
DE: 8424 Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8135)
DE: 8445 Experimental volcanism
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting