NOVELTY - The apparatus includes heating element enclosing cylindrical capsule region. The sleeve element is adapted to form sealed region to enclose heating element. An internal pressure level of sealed region tightens contact between sleeve element and seal. The gas pressure intensifier is used for pumping gaseous species. The sleeve element is formed from bridgman seal, Grayloc seal (RTM: unique device for connecting piping systems), or o-ring seal. The high strength enclosure material is placed over annular ceramic element to form high strength enclosure (101).    USE - Apparatus for processing high pressure material in supercritical fluids used for manufacturing gallium-containing crystal wafers for mounting optoelectronic unit such as LED, laser diode, photo detector, avalanche photodiode transistor, rectifier, thyristor, Schottky rectifier, positive-intrinsic-negative (PIN) diode, metal-semiconductor-metal diode, high-electron mobility transistor, metal semiconductor FET, metal oxide FET, power metal oxide semiconductor FET, power metal insulator semiconductor FET, bipolar junction transistor, metal insulator FET, heterojunction bipolar transistor, power insulated gate bipolar transistor, power vertical junction FET, cascode switch, inner sub-band emitter, quantum well infrared photo detector, quantum dot infrared photo detector, solar cell, and diode (all claimed) for photo electrochemical water splitting and hydrogen generation.    ADVANTAGE - Since the high strength enclosure material enables an enclosure to withstand a load greater than about 0.1 GPa at a temperature of about 200 degrees C. The apparatus for processing high pressure material can be rocked so as to facilitate convection of the supercritical fluid within the capsule. The electrical circuits for each heating element segment are independently controlled to provide flexibility so as to achieve and maintain a heat deposition profile along the capsule height. The torque on gasket can be minimized during tightening of grand nut. The winding patterns of the heating elements and the resultant isotherms with minimal temperature gradient spacing can minimize or eliminate wall nucleation inside the capsule and on the baffle. The pressure control device can adjusts the internal pressure within the capsule and the surrounding pressure in closed or sealed environment through the gas pressure intensifier to balance the internal and surrounding pressures, so that the pressure difference can be eliminated and displacement of the capsule can be prevented. The capsule can withstand relatively higher internal pressures, so as to facilitate processing of materials with supercritical fluids. The pressure difference can be eliminated or minimized by simultaneously control of temperature and pressure in tandem within the capsule. The insulation material can enhance or improve the process stability.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method for operating high pressure crystal growth apparatus.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the high pressure apparatus.    Enclosure (101)    Radial segments (103)    Sleeve (105)    Heater (107)    Capsule (109)