21. Rothstein likens these transporters to " little vacuum pumps ." 22. During the 1930s, improvements in vacuum pumps made vacuum deposition methods, like sputtering, possible. 23. Helix is a leading supplier of vacuum pumps that are needed to make semiconductors. 24. Maintaining a vacuum in the liquid ring vacuum pump is used for this purpose. 25. He demonstrated the vacuum pump to separate the pairs of copper hemispheres using air pressures. 26. Helix develops low-temperature devices and vacuum pumps for makers of electronic parts, such as semiconductors. 27. The first support meeting I went to they brought out vacuum pumps and the like, 28. In 1922, he was trying to develop an industrial vacuum pump for vacuuming iron filings. 29. That tube was evacuated by the highly effective mercury vacuum pump created by Hermann Sprengel. 30. Typically, a vacuum pump is used to remove the air from the empty heat pipe.
