Abstract: A method for treating a silicon plate, a so-called wafer, in a cold-wall reactor when using the so-called CVD-technique in order, among other things, to deposit substances on the silicon plate by introducing different gases into the reactor. The reactor is configured as a microwave cavity, and one treatment stage involves introducing microwave energy into the reactor from a microwave generator, thereby to heat the silicon plate to a desired temperature, which is measured in a known manner. According to one preferred embodiment, a suitable etching gas is introduced into the cold-wall reactor, and microwave energy is then introduced into the reactor at a power level such as to form a plasma in the reactor, to thereby back-etch a substrate or to clean the reactor from possible impurities contained therein.

Abstract: A method for heating thick-walled glass tubes, particularly quartz tubes, in the manufacture of optical fibres while using microwave energy. According to the invention, the tube (5) is pre-heated to a temperature of about 1000.degree. C.-1500.degree. C., preferably in a known manner with the aid of a gas flame, whereafter the tube is further heated by means of microwave energy, generated by a microwave generator, by inserting the tube (5) axially into a microwave cavity (2) incorporating in both end walls (6,7) or end surfaces openings (3,4) for the tube (5), the electrical field strength being given a field image which includes only one tangential component, according to TE-01n-mode, preferably according to the mode TE-011, whereby the electrical field is so formed as to be tangential to the surfaces of the tube (5), and so formed that the electrical field strength is zero adjacent the surfaces of the cavity (2). The invention also relates to apparatus for carrying out the method.

Abstract: A method of heating glass tubes, particularly quartz tubes for the manufacture of optical fibres, where the tube is pre-heated, preferably by means of a gas flame, whereafter the tube is heated by means of microwave energy generated by a microwave generator (1), by introducing the tube axially into a microwave cavity (3) comprising in its end walls (6,7) or end surfaces openings for the tube. According to the invention, at least one electrical field is given a field image according to a TM-0n0-mode, preferably according to the TM-020-mode, which mode has a maxima (10) along the central axis (9;c-c) of the cavity (3) and a minima (11,12) on each side of and radially spaced from the central axis (9;c-c), where the electrical field portion located between the minima (11,12) is used for heating the wall of the glass tube (8).

Abstract: A method of heating objects by microwave energy by supplying microwave energy from a generator to a first waveguide. A second waveguide is located, separated from the first waveguide except for at least one parallel and adjacent coupling distance at a common wall between the waveguides. A coupling of microwave energy distributed in the wave propogation direction of the waveguides takes place at the coupling distance so that microwave energy passes from one waveguide to the other one. The second waveguide is dimensioned, so that action of load (objects being heated) conducts microwave energy in the second waveguide with the same wave phase constant as the first waveguide. Objects to be heated are fed only into and out of said second waveguide. A uniform field is fed-in only into the first waveguide. A uniform field distribution and heating profile is obtained and leakage of microwave energy from the open ended second waveguide is avoided.