NASA 1998 SBIR Phase I


PROPOSAL NUMBER: 98-1 15.01-4884

PROJECT TITLE: Ultra Low Weight Turbomolecular Pump

TECHNICAL ABSTRACT (LIMIT 200 WORDS)

This project proposes design, manufacture, and testing of an ultra-low weight and volume hybrid turbomolecular pump (TMP). The pump will provide a pumping speed density of roughly 100 l/s/kg (state of the art is 50 l/s/kg) while keeping the pump diameter to ~ 2" and pump length to ~ 5". Innovative features include: 1. A high speed (~200,000 rpm), one piece, titanium rotor with a specially designed first stage, integral Siegbahn-type drag stages, and conical retention features (one that is solenoid actuated) on each end which permit restraint during periods of shock loading (e.g. during launch). 2. A first turbo stage with tapered blade cross-sections, zero radius bore, and a mid-span damper ring to provide very low hub-to-tip radius ratio (~.5), excellent vibration characteristics, large inlet area, and high tip speed (>1800 ft/s). 3. Shrouded late stage rotors with helicoid stator surfaces to act as a parallel molecular drag stages thus providing very high stage pressure ratios (>20) and low ultimate pressure (1e-09 Torr). 4. Unique rotor geometries for each stage with curved and twisted blades which will allow very high-pressure ratio (~ 107 on H2) and minimum stage count (~5). 5. Magnetic bearings, a high turns density motor, and thin lightweight titanium housings and flanges. This system will provide a hybrid turbomolecular pump uniquely suited for instruments deployed in space for in-situ sensing. The pump will supply ~ greater than 50 l/s pumping speed while weighing ~ 1lbm.

POTENTIAL COMMERCIAL APPLICATIONS

The advances proposed here have particular advantage where weight and volume are at a premium. These technologies will lead to a hybrid turbomolecular pump that offers 100 l/s/kg (compared to 50 l/s/kg for present state of the art). Therefore the pump should have advantage in space applications. Furthermore, because the rotors and housings will be much smaller for a given pumping speed, there exists a substantial potential cost reduction for pumps that are larger than 500 l/s. When considering the entire market that could be reached by these technologies the potential is substantial (on the order of 1 billion dollars/yr). However, PADT's market analysis has been confined to three initial markets: space in-situ mass spectrometers, commercial portable mass spectrometers, and semiconductor low pressure plasma vapor deposition reactors. It is difficult to predict the exact size of these markets but analysis has provided rough orders of magnitude. The space in-situ mass spectrometer market is on the order of $10 million/yr. The hybrid pump concept developed here would work well in missions where the exhaust pressure is on the order of 10 Torr (then no backing pump would be required). Several NASA missions are planned which might employ a lightweight turbomolecular pump including trips to Europa, Jupiter, and Mars. Additionally, test labs may also need to use small turbomolecular pumps as part of their ground based testing. The portable mass spectrometer market is on the order of $100 million/yr. Possible applications include: defense related mass spectrometry systems designed to detect contagions at very low concentration; medical mass spectrometers which are designed to aid in patient diagnoses; or portable detectors which could be used for security reasons in airports or hotels. The semiconductor wafer fabrication market is on the order $500 million/yr. Possible applications include low-pressure plasma deposition reactors.

NAME AND ADDRESS OF PRINCIPAL INVESTIGATOR

Dr. Mark C Johnson
Phoenix Analysis and Design Technologies
4123 E. Coolidge
Phoenix , AZ 85018

NAME AND ADDRESS OF OFFEROR

Phoenix Analysis and Design Technologies
1465 N. Fiesta Blvd. Suite 107
Gilbert , AZ 85233