Abstract: A heat exchanger 10 comprises a pressure vessel 14 having a feed inlet 11 in an upper part thereof for particulate material to be subjected to heat exchange and an outlet 13 at a lower part thereof for the outflow of particulate material from the vessel 14. A plurality of heat exchange elements, such as heat exchange plates 12, arranged in spaced relationship inside the pressure vessel 14 to define flow passages between adjacent heat exchange elements 12 is provided for particulate material to flow therethrough under the force of gravity. The pressure vessel 14 has an inside wall extending around the heat exchange elements 12 and further comprises a trap, such as a baffle 22, between the heat exchange elements 12 and the inside wall for trapping particulate material leaking from the flow passages between the heat exchange elements 12 to form a gas barrier 26 between the heat exchange elements 12 and the pressure vessel 14.

Abstract: This disclosure presents an alternative, improved approach to the RF only quadrupole mass spectrometers. The ions whose masses place them near the stability limit for a given operating voltage and RF frequency, can be strongly influenced by the application of a very small dc voltage to the quadrupole rods. If this voltage is modulated at a low frequency (typically a few hundred hertz), the (a,q) values will pass alternately through the stability boundary and ions will be transmitted with the imposed frequency. The advantages of the new approach are two-fold (a) lock-in amplifier synchronous detection schemes can be used. These give improved signal/noise ratios. Background noise due to photons, soft X-rays or excited neutrals--often a problem in quadrupole mass filters--will not be modulated and will not be detected. (b) Higher resolution can be achieved.

Abstract: A tandem quadrupole mass spectrometer system having first, second and third quadrupole sections close coupled in series with one another. AC-only is applied to the center section and conventional AC and DC voltages are applied to the two end sections. The AC applied to all three sections is synchronized in frequency. The AC phase shift between each section is of magnitude between 0 and 0.1 cycles in absolute value, preferably between 0 and 0.03 cycles in absolute value, and in the preferred embodiment the AC phase shift between each section is essentially zero. The sections are spaced apart longitudinally by a very short distance not exceeding r.sub.o, the radius of the inscribed circle within the quadrupole rods.

Abstract: The quadrupole mass spectrometer has four conventional rod-shaped poles symmetrically located about the ion injection axis. Opposite pairs of rods are interconnected and connected to an rf voltage source. A shield having a circular aperture is located at the output end of the rods to assure the stoppage of low mass particles. In addition, a stopping element also preferably circular is located on the axis at the output to assure the stoppage of heavy particles. A pair of grids incorporating the stopping element, are sequentially located at the output, normal to the axis, the first is connected to a dc voltage source to accelerate the remaining particles through the fringing field of the quadrupole and the second is connected to a dc voltage source to subsequently decelerate the particles.