In high-energy physics, precision optics, and semiconductor manufacturing, "ultimate vacuum level, thermochemical stability, and anti-backstreaming purity" define the gold standard for diffusion pump fluids. Conventional hydrocarbon-based diffusion pump oils, while inexpensive, readily pyrolyze under high-temperature jets, contaminating high-vacuum chambers with tars and coke. Standard polyphenylmethylsiloxanes offer improvements but still struggle to prevent the backstreaming of light fractions during prolonged high-temperature operation, leading to vacuum fluctuations. Driven by the stringent demands of synchrotron radiation sources, semiconductor thin-film deposition, and high-resolution mass spectrometry for "ultimate vacuum reaching 10⁻⁸ Torr, saturated vapor pressure as low as 5×10⁻⁸ Torr, and thermal-oxidative resistance without coking," a high-phenyl-content silicone fluid—CAS 3982-82-9, C₂₈H₃₂O₂Si₃, MW 484, Flash Point ≥210°C—has become the critical consumable for maintaining the "absolute vacuum" essential to cutting-edge research and industrial production. Addressing this "high-vacuum fluid" gap, Anhui IOTA Silicone Oil Co., Ltd. (IOTA) officially releases High Vacuum Diffusion Pump Oil IOTA 704. Defined by core parameters—colorless transparent oily liquid, Chemical Name: Tetramethyl Tetraphenyl Trisiloxane, Refractive Index 1.5500-1.5600, Congealing Point -35°C—it carries the triple genetic traits of "extreme vacuum, thermal stability without coking, and rapid pump-down," serving as the "vascular blood" for CRT manufacturing, optical coating, and high-vacuum metallurgical furnaces. Molecular Architecture: The Vacuum Code of Phenyl Shielding The core leverage of IOTA 704 stems from its compact topological structure—Tetramethyl Tetraphenyl Trisiloxane:

• Extreme Vacuum Gene: The high phenyl (Ph) side-group content significantly enhances molecular thermal stability while drastically reducing saturated vapor pressure (down to 5×10⁻⁸ Torr). This structure ensures that even when heated above 200°C, few light molecules escape into the high-vacuum region, effortlessly achieving an untrapped ultimate vacuum of 10⁻⁷~10⁻⁸ Torr.
• Thermal-Coking Barrier: The incorporation of phenyl groups creates substantial steric hindrance, effectively resisting high-temperature oxidation and cracking. Even in scenarios involving accidental air leaks while the pump is hot, IOTA 704 remains chemically inert, preventing the formation of gums, tars, or hard carbon deposits on jets or pump walls, thereby extending oil life and maintenance intervals.
• Rheological Balance Design: The kinematic viscosity of 38±3 cSt (25°C) and density of 1.06-1.07 are precisely calibrated to diffusion pump jet dynamics. This ensures high-speed steam ejection and momentum transfer at the nozzle while guaranteeing smooth condensate return, resulting in rapid pump-down and high pumping efficiency.
• Wide-Temp Fluid Character: A congealing point of -35°C ensures start-up capability in cold environments, while a high flash point (≥210°C) provides ample operational safety margins across various harsh industrial settings.

Performance Leap: From Deep Evacuation to Clean Processes In electronics manufacturing, optical coating, vacuum metallurgy, and scientific research facilities, IOTA 704 demonstrates performance leaps beyond conventional pump oils:

• Electro-Optical Cleanliness: In production lines for B/W & color picture tubes, fluorescent lamps, CRTs, and incandescent bulbs, it ensures the purity of internal high-vacuum environments, preventing efficiency drops or electrode leakage caused by oil backstreaming.
• Optical Coating Foundation: Serving as the working fluid in deposition systems for anti-reflective lens coatings, optical filters, and mirrors, its low backstreaming characteristic guarantees coating uniformity and high transmittance, avoiding light scattering losses due to oil film contamination.
• Metallurgical Vacuum Assurance: Providing stable, reliable high-vacuum environments for sintering, melting, degassing, and thick-film deposition of refractory metals (W, Mo, Ta), ensuring the high purity and density of metallic materials.
• Scientific Precision Support: Supporting particle accelerators, molecular distillation units, mass spectrometers, and various R&D high-vacuum systems with extremely low background pressures to ensure experimental accuracy and reproducibility.

Application Penetration: From Basic Lighting to Frontier Physics IOTA 704 precisely targets domains triply sensitive to "vacuum level, cleanliness, and reliability":

• Electrical & Electronics: Vacuum impregnation of capacitors, metallized film deposition in rectifiers, evacuation of various electro-vacuum devices.
• Optics & Photonics: Spectacle lens coating, laser mirror fabrication, precision coating of optical filters.
• Advanced Manufacturing: Specific semiconductor IC process steps, surface modification coatings for precision plastic parts.
• Research Infrastructure: Ultra-high vacuum subsystems within national mega-science projects (e.g., synchrotron radiation, nuclear fusion research).

IOTA Technical Guide: Dedicated Fluid, Periodic Monitoring

• Charging Protocol: Fill IOTA 704 only after ensuring the diffusion pump system is clean and dry. Refer to the specific pump model for fill volume; overfilling or underfilling will impair performance.
• Warm-up Procedure: Ensure the water cooling system is operational before activating the heater. It is recommended to operate the backing mechanical pump first; only after the system reaches rough vacuum (<10 Pa) should the diffusion pump heater be activated to gradually reach operating temperature.
• Leak Management: Although IOTA 704 exhibits excellent resistance to atmospheric exposure, system leaks must be rigorously prevented. If the pump remains hot while exposed to air for extended periods, inspect oil quality and replace if necessary to prevent degradation.
• Storage & Transport: Available in 1kg bottles, 1-gallon drums, 5kg/25kg plastic drums, and 25kg/200kg iron drums. Transported as non-hazardous chemicals; protect from rain, moisture, and direct sunlight. Shelf life: 3 years under sealed conditions.

Industry specialists note that diffusion pump oil is the "blood" of vacuum acquisition systems. The successful localization of IOTA 704 not only breaks the long-standing monopoly of foreign brands in high-end diffusion pump fluids but also provides a domestically controllable supply chain guarantee for China's high-energy physics research, precision optical manufacturing, and semiconductor industries, matching the performance metrics of top-tier international brands (e.g., Dow Corning 704). This marks that domestic specialty silicones have acquired the hardcore strength to compete on par with global giants in extreme-condition and ultra-high-purity application domains.