One aspect relates to a process for the preparation of a quartz glass body, including providing a silicon dioxide granulate, making a glass melt out of silicon dioxide granulate and making a quartz glass body out of at least part of the glass melt. The silicon dioxide granulate is obtained by providing and processing a silicon dioxide powder. One aspect also relates to silicon dioxide granulate, which is obtained by providing a silicon dioxide powder and processing it. One aspect further relates to a quartz glass body which is obtainable by this process. One aspect further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, ii.) Making a glass melt from the silicon dioxide granulate in an oven, and iii.) Making a quartz glass body from at least a part of the glass melt, wherein the oven comprises a hanging sinter crucible. The invention also relates to a quartz glass body which is obtainable by this process. The invention further relates to a light guide, an illuminant and a formed body which are each obtainable by further processing the quartz glass body.

One aspect relates to a process for the preparation of a quartz glass body. The process includes providing a silicon dioxide granulate from a pyrogenically produced silicon dioxide powder, making a glass melt out of silicon dioxide granulate, and making a quartz glass body out of at least part of the glass melt. The size of the quartz glass body is reduced to obtain a quartz glass grain. The quartz glass body is processed to make a preform and an opaque quartz glass body is made from the preform. One aspect further relates to an opaque quartz glass body which is obtainable by this process. One aspect further relates to a reactor and an arrangement, which are each obtainable by further processing of the opaque quartz glass body.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing silicon dioxide particles, ii.) Making a glass melt out of the silicon dioxide particles in an oven and iii.) Making a quartz glass body out of at least part of the glass melt, wherein the oven has a gas outlet through which gas is removed from the oven, wherein the dew point of the gas on exiting the oven through the gas outlet is less than 0 C. The invention further relates to a quartz glass body which is obtainable by this process. The invention further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

A glass fiber according to the present invention is suitable for preventing filament breakage and suitable for being stably produced for a long term, and has a ?-OH value of 0.02 mm.sup.?1 or more and less than 0.55 mm.sup.?1. The preferred content of SO.sub.3 is more than 0 ppm and 70 ppm or less on a mass basis. The glass fiber is preferably substantially free of As and Sb. SO.sub.3 can be supplied to a glass raw material as, for example, a sulfuric acid salt of an alkali metal or an alkaline-earth metal.

One aspect relates to a process for the provision of a quartz glass body, including providing a silicon dioxide granulate, making a glass melt from the silicon dioxide granulate in an oven and making a quartz glass body from at least part of the glass melt. The oven includes a hanging metal sheet crucible. One aspect also relates to a quartz glass body which is obtainable by this process. One aspect further relates to a light guide, an illuminant and a formed body which are obtainable by processing the quartz glass body further.

The invention relates to a process for preparing a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, ii.) Making a glass melt from the silicon dioxide granulate in a melting crucible, and iii.) Making a quartz glass body from at least a part of the glass melt, wherein the melting crucible is comprised in an oven and is made of at least one material comprising tungsten or molybdenum or a combination thereof. The invention further relates to a quartz glass body which can be obtained by this process. Further, the invention relates to a light guide, an illuminant and a formed body, each of which can be obtained by processing the quartz glass body further.

One aspect relates to a light guide comprising a jacket and one or more cores, wherein the jacket surrounds the cores. Each core has a refractive index profile perpendicular to the maximum extension of the core, wherein at least one refractive index n.sub.K of each refractive index profile is greater than the refractive index n.sub.M1 of the jacket. The jacket is made of silicon dioxide and has an OH content of less than 10 ppm, a chlorine content of less than 60 ppm, and an aluminium content of less than 200 ppb. One aspect also relates to a silicon dioxide granulate I, characterized by a chlorine content of less than 200 ppm and an aluminium content of less than 200 ppb, in each case based on the total weight of the silicon dioxide granulate I.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, wherein the silicon dioxide granulate was made from pyrogenic silicon dioxide powder and the silicon dioxide granulate has a BET surface area in a range from 20 to 40 m.sup.2/g, ii.) Making a glass melt out of silicon dioxide granulate in an oven and iii.) Making a quartz glass body out of at least part of the glass melt, wherein the oven has at least a first and a further chamber connected to one another via a passage, wherein the temperature in the first chamber is lower than the temperature in the further chambers. The invention further relates to a quartz glass body which is obtainable by this process. The invention further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, ii.) Making a glass melt out of the silicon dioxide granulate and iii) Making a quartz glass body out of at least part of the glass melt, wherein the provision comprises the steps I. Providing a silicon dioxide powder with at least two particles made from a silicon-chlorine compound, II. Bringing the silicon dioxide powder into contact with steam to obtain a treated silicon dioxide powder and III. Granulating the treated silicon dioxide powder to obtain a silicon dioxide granulate, and wherein the chorine content of the silicon dioxide powder is greater than the chlorine content of the silicon dioxide granulate. The invention further relates to a quartz glass body which is obtainable by this process. The invention further relates to a process for providing a silicon dioxide granulate. The invention further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.