1-2
chamber for vacuum, pressure, instrumentation, and cooling, the individual
components function as a system to control temperature, pressure, and process
atmosphere.
• The chamber is designed for vacuum or pressure and incorporates a lid
latching mechanism for rapid entry and automatic sealing. Both the lid and
chamber are machined from solid 6061-T6 aluminum billet and are rated for
operation from less than 100 millitorr vacuum to a maximum positive pressure
of 50 psig. All internal surfaces and components are finely machined to
enhance vacuum performance and reduce evacuation time. With the lid in the
open position the working surface of the target plate is flush with the chamber
sealing flange and machine enclosure to facilitate fine hand manipulation and
viewing of components and tooling.
• Directly below the target plate and heating element, hermetically sealed
electrodes enter the chamber through the bottom wall. Although the element
is connected directly to the electrodes and suspended on ceramic rods, heat
losses are kept to a minimum because the contacting areas are very small and
the ceramic rods and electrodes are thermally isolated from the chamber.
Additional thermal isolation is provided by surrounding the heating element
with a highly polished radiation shield to prevent direct radiation from
reaching the chamber, lid, or view port. Directly below the lower radiation
shield a centrally located port provides diffused gas flow for cooling, purging,
or for introduction of N
2
/formic acid, (optional), when required by the
process.
• The lid assembly incorporates a 3.5 in. (8.9 cm) diameter water-cooled view
port assembly located directly over the target; clearance between target plate
and window is fixed at 4.0 in. (10.2 cm). The view port is mounted in a dual-
walled housing that is bolted directly to the lid; radiated energy from the
target plate, being of relatively long wave length, is readily absorbed by the
borosilicate sight glass which necessitates cooling, particularly when
operating the furnace for prolonged periods above 300 °C. Directly above the
target plate the lid incorporates a milled pocket providing .80 in (2.0 cm)
clearance above the target plate in areas that are not directly below the view
port. An array of angled holes, drilled directly into the lid along the edges of
the milled pocket, are connected together with internally drilled passages to
the gas distribution system which generates turbulent flow across the entire
work area for rapidly cooling parts and fixtures to safe handling temperatures.
• To dissipate heat generated from potentially high process temperatures, the
lid, chamber, and view port housing are continuously water-cooled. Both the
chamber and lid are manufactured with integral coolant passages formed using
deep-drilled holes. The high thermal conductivity of the base material,
together with the size and placement of the passages, keeps the lid and
chamber within a few degrees of each other throughout the operating range of
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