Abstract: The disclosed invention describes an apparatus and method for bringing a system having high interactive portions to a predetermined temperature distribution. The invention includes a difference controller which provides, through two separate drivers, a fixed total amount of energy to the system being controlled. If the system being controlled also has a long cycle time, second and third temperature controllers may be used to bring the system to the equilibrium temperature with a minimum amount of overshoot. The invention is particularly advantageous when used in connection with a high pressure, high temperature vessel useful in growing quartz crystals.

Abstract: The invention relates to means for establishing an equalized pressure across the insulating sheath of a hot isostatic press system. Tubes are positioned in the outer, insulation portion of the sheath to provide a substantially resistance free passage between a source of high pressure gas input to the system and the upper portions of the sheath. The invention also tends to reduce convection currents in the furnace chamber.

Abstract: The disclosed invention describes an apparatus and method for bringing a system having high interactive portions to a predetermined temperature distribution. The invention includes a difference controller which provides, through two separate drivers, a fixed total amount of energy to the system being controlled. If the system being controlled also has a long cycle time, second and third temperature controllers may be used to bring the system to the equilibrium temperature with a minimum amount of overshoot. The invention is particularly advantageous when used in connection with a high pressure, high temperature vessel useful in growing quartz crystals.

Abstract: Method for compacting preheated powder bodies in a high pressure isostatic pressure vessel in which a liquid such as water is used as the pressurizing medium. A preheated workpiece is inserted into the vessel which is closed and sealed. The vessel is then rapidly filled with the liquid pressurizing medium while avoiding contact of the medium with the preheated workpiece until the vessel is substantially completely full. The pressure within the vessel is then increased rapidly to a preselected compacting level by continually pumping the liquid pressurizing medium into the vessel. The preselected compacting pressure is in excess of the critical pressure of the liquid pressurizing medium. The rapid increase of pressure within the vessel to a level exceeding the critical pressure minimizes the amount of vapor that is formed in the vessel and reduces heat transfer from the preheated body to the pressurizing system.