Turbomolecular Vacuum Pump

What is the Turbomolecular Vacuum Pump?

A turbomolecular pump uses rapidly rotating blades to reach high and ultra-high vacuum below 10⁻⁶ mbar. It is used for electron microscopy, surface analysis, coating and semiconductor processes where clean high vacuum is essential.

Overview

The turbomolecular pump has a rotor with many angled blades alternating with stator blades. Fast-moving blades transfer momentum to gas molecules and drive them toward the exhaust, where a backing pump removes them. Rotor speeds reach 20,000 to 90,000 revolutions per minute, so bearings are either ceramic ball bearings or magnetic bearings. Ultimate pressure can be below 10⁻⁷ to 10⁻¹⁰ mbar, depending on the number of stages and the backing pressure, and pumping speeds range from a few to several thousand liters per second. Turbopumps are clean, oil-free and vibration-isolated, and they must never be vented to atmosphere at full speed or exposed to high gas loads without a suitable backing pump. They are essential for electron microscopes, mass spectrometers, surface analysis and thin-film deposition.

How does it work?

Vacuum pumps remove gas molecules to lower pressure in a sealed volume. Positive-displacement types, including rotary vane, diaphragm, scroll and roots pumps, trap a volume of gas and push it out. Momentum-transfer pumps, including turbomolecular and diffusion pumps, accelerate molecules toward an exhaust that a backing pump removes. Water-ring and ejector pumps use a liquid or a jet to entrain and carry gas away. Performance is described by ultimate or base pressure and by pumping speed, which is measured in liters per second or cubic meters per hour. Real performance also depends on the gas load, on outgassing from chamber walls, and on the conductance of the connecting piping. Vapor handling, corrosion resistance and cleanliness determine which pump suits a given process, and pumps are often combined in stages to cover a wide pressure range.

What are the key features?

• Ultimate pressure below 10⁻⁷ to 10⁻¹⁰ mbar
• Rotor speeds of 20,000–90,000 rpm
• Pumping speeds from a few to thousands of L/s
• Ceramic ball or magnetic bearing options
• Clean, oil-free and low-vibration operation
• Requires an appropriate backing pump

What are the technical specifications?

A typical turbomolecular vacuum pump configuration offers ultimate pressure of Below 10⁻⁷–10⁻¹⁰ mbar, pumping speed (N2) of 50–3,000 L/s, rotor speed of 20,000–90,000 rpm, compression ratio (N2) of 10⁸–10¹¹, bearing type of Ceramic ball or magnetic and backing pressure of Below 0.1 mbar. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Turbomolecular Vacuum Pump is used in electron microscopy, surface analysis and XPS, mass spectrometry, thin-film deposition and semiconductor and coating processes. Across the wider Vacuum Pumps class, laboratories also deploy it for chamber evacuation for drying and degassing, rotary evaporation and distillation and freeze drying and centrifugal concentration.

Which standards and certifications apply?

Relevant standards and methods include IEC 61010-1, IEC 61326-1, ISO 21360, ISO 27893, ISO 20485 and GB 4793.1. Certification candidates for this model are CE, RoHS and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Protect the pump from the process with a cold trap, foreline trap or filter, and vent to atmosphere before switching off a high-vacuum pump. Change oil and check seals on schedule for oil-sealed pumps, and inspect scroll tips and diaphragms for dry pumps. Keep tubing as short and wide as possible to preserve conductance, and use the correct flange type and vacuum grease sparingly. Monitor pressure with gauges appropriate to the range, such as Pirani, capacitance or ion gauges. Follow IEC 61010-1 for electrical safety and local pressure equipment rules. For oil-free or clean processes, confirm that the pump cannot backstream oil or particles. Record base pressure and pump-down curves during commissioning and at each service so that degradation is detected early.

How do I select the right Turbomolecular Vacuum Pump?

Choose a turbopump for high and ultra-high vacuum where cleanliness is essential. Always specify a matched backing pump and pressure gauge. In the RFQ, state target pressure, gas load, inlet flange, cooling and whether magnetic bearings are required.

How does it compare with other Vacuum Pumps variants?

Work from the required working pressure, the gas composition and the volume to be evacuated. For rough vacuum in filtration and drying, a diaphragm or single-stage rotary vane pump is sufficient. For medium vacuum in rotary evaporation and coating, a two-stage rotary vane or scroll pump is appropriate. For high and ultra-high vacuum in electron optics, surface analysis and semiconductor work, a turbomolecular pump with a suitable backing pump is needed. Consider whether the gas is condensable, corrosive or particle-laden, and add traps, filters and corrosion-resistant materials as required. Size pumping speed from the chamber volume, the target pressure and the acceptable pump-down time, remembering that conductance limits real speed. Decide between oil-sealed and dry designs based on contamination risk, and specify gauges, valves and controllers as part of the system.