Turbo molecular pump

Schematic representation of the experimental setup is shown in Fig 1.1. The electrochemical system is coupled on-line to a Quadrupole Mass Spectrometer (Balzers QMS 311 or QMG 112). Volatile substances diffusing through the PTFE membrane enter into a first chamber where a pressure between 10 1 and 10 2 mbar is maintained by means of a turbomolecular pump. In this chamber most of the gases entering in the MS (mainly solvent molecules) are eliminated, a minor part enters in a second chamber where the analyzer is placed. A second turbo molecular pump evacuates this chamber promptly and the pressure can be controlled by changing the aperture between both chambers. Depending on the type of detector used (see below) pressures in the range 10 4-10 5 mbar, (for Faraday Collector, FC), or 10 7-10 9 mbar (for Secondary Electrton Multiplier, SEM) may be established.

The glass coating process requires high gas flows for the sputter processes as well as low hydrocarbon concentration. The only vacuum pump which satisfies these requirements as well as high pumping speed stability over time are turbo-molecular pumps which are used almost exclusively. 

Vacuum technology acceptance specifications for turbo-molecular pumps 11/78... 

Fig. 11 High pressure, high temperature STM. Sections A-UHV sample manipulator with indirect heating and cooling, B-variable temperature STM, C-magnetically coupled linearrotary transfer arm, D-optical access for analyzers. E-pneumatic air legs and suspension frame, F-turbo molecular pump, G-ion pump. ...

TURBO MOLECULAR TURBO MOLECULAR PUMPING STAGE 3 PUMPING STAGE 2... 

Fig. 1. Photo and illustration of the HRTEM allowing acquisition of images of catalysts under working conditions (4). The microscope is equipped with an FEG, a quadrupole mass spectrometer (QMS), a Gatan image filter (GIF), and a Tietz F144 CCD for data acquisition. The differential pumping system consists of IGPs, turbo molecular pump units (TMP, MDP), and an oil diffusion pump (ODP). The differential pumping stages are set up by apertures inside the TEM column (denoted by black bars) at the objective lens (OL), the first (Cl) condenser aperture, the second (C2) condenser aperture, and the selected area aperture (SA).

A two-stage, oil-sealed rotary vane pump is used to back a turbo-molecular pump via a DN25KF line (see below). Under normal working conditions, the pressure in the backing line is (2 to 6) x 10 3mbar. Would the TMP become contaminated by the backing pump ... 

The vacuum system of the instrument consists of a four-stage, internally integrated membrane pump with an ultimate pressure of about l-2mbar. The final vacuum is reached with a 70 L/s turbo molecular pump. 

The ultrathin porous glass membranes were examined for the permeability of air at 25°C. The measurements were performed as follows The membrane was sticked on a brass plate containing a bore with 2 and 5 mm diameter, respectively. After that, the plate was fixed with a special dome on a turbo molecular pump (TMU 261, Pfeiffer). Now, the dome was evacuated. The gas flow was determined by measuring the pressure below the membrane. Finally, the integral permeability was estimated using the pumping speed, the measured pressures and the membrane thickness. 

Adsorption equilibria and uptakes were gravimetrically measured with two balances, i.e., Cahn 1100 microbalance and Magnetic Suspension Balance (Rubotherm Co.). Adsorbents were loaded and regenerated in the balance under the flow of ultra high purity Helium gas at ISO 3S0 C, then adjusted to the measuring temperature and evacuated to 10 mmHg by using a turbo molecular pump. Adsorbates used were as follows propane (min.99.5), isobutane (min.99.5%), n-butane (min.99.S%), 1-butene (min.99.5%), isobutene (min.99.5%) and t-2-butene (min.99.8%). 

Without the target gas, the vacuum in the chamber is usually maintained at 10 —10 torr by a suitable pump, which is usually either a well trapped diffusion pump or a turbo-molecular pump. When the gas target is introduced the vacuum is generally maintained at about 10 torr. 

The first chamber hosts the cluster source, evacuated by two turbo-molecular pumps (3001/s). They are horizontally mounted facing each other, in order to assure the correct operating conditions for the pulsed supersonic... 

The XPS spectra were obtained using an ESCA SSX-100 spectrometer (SSL) equipped with a monochromatized A1 Ka X-ray source. AU the samples were introduced into the preparation chamber under a high purity N 2 gas atmosphere and evacuated with a turbo molecular pump. 

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