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.

An enclosure for providing a controlled environment includes a central plane extending through a top end of the enclosure and a bottom end of the enclosure and bisecting the enclosure along a width of the enclosure, an inlet at the bottom end of the enclosure having an inlet width, W.sub.inlet, an enclosure wall extending from the inlet to the top end of the enclosure, an entry port at the top end of the enclosure, and an outlet between the entry port and the chamber region of the enclosure wall. The enclosure wall comprises a chamber region and a transition region between the inlet and the chamber region. The width of the chamber region, W.sub.chamber, is substantially constant through the chamber region. The width of the enclosure in the transition region decreases from W.sub.chamber to W.sub.inlet, and a ratio of W.sub.inlet to W.sub.chamber is from 1:2 to 1:5.

An enclosure for providing a controlled environment includes a central plane extending through a top end of the enclosure and a bottom end of the enclosure and bisecting the enclosure along a width of the enclosure, an inlet at the bottom end of the enclosure having an inlet width, W.sub.inlet, an enclosure wall extending from the inlet to the top end of the enclosure, an entry port at the top end of the enclosure, and an outlet between the entry port and the chamber region of the enclosure wall. The enclosure wall comprises a chamber region and a transition region between the inlet and the chamber region. The width of the chamber region, W.sub.chamber, is substantially constant through the chamber region. The width of the enclosure in the transition region decreases from W.sub.chamber to W.sub.inlet, and a ratio of W.sub.inlet to W.sub.chamber is from 1:2 to 1:5.

A drinking implement includes a first end section with a first opening and a second end section with a second opening. A wall made of glass extends from the first opening to the second opening. At least one of the first end section or the second end section is designed as a specific end section having at least partially a ridge, an outer edge, and an inner edge. An outer transition angle and an inner transition angle both have absolute values of less than 90 degrees.

A glass tube element having a hollow cylindrical section with a shell having an outer diameter is provided. A first ratio is a difference value to a mean value. The difference value is a difference of a minimal and maximal value of the outer diameter. The mean value is a mean of the minimal and maximal values. A sub-section having a start, an end, and a distance of 1 meter measured along a straight line from the start to the end and intersecting with a center axis of the sub-section at the start and the end. The sub-section having, for every point of the center axis, a shortest distance to the straight line. A second ratio of a specific distance to 1 meter, the specific distance being defined as a largest of all shortest distances. A product of the first and second ratio is smaller than 4×10.sup.−6.

A glass tube element having a hollow cylindrical section with a shell having an outer diameter is provided. A first ratio is a difference value to a mean value. The difference value is a difference of a minimal and maximal value of the outer diameter. The mean value is a mean of the minimal and maximal values. A sub-section having a start, an end, and a distance of 1 meter measured along a straight line from the start to the end and intersecting with a center axis of the sub-section at the start and the end. The sub-section having, for every point of the center axis, a shortest distance to the straight line. A second ratio of a specific distance to 1 meter, the specific distance being defined as a largest of all shortest distances. A product of the first and second ratio is smaller than 4×10.sup.−6.

A glass tube element having hollow cylindrical section that has a shell enclosing a lumen and extends along a main extension and an optical delay of a light ray. The shell has a surface facing away from the lumen. The optical delay has values that all fall within a range having a size of between 3 and 30 nm. The optical delay being an optical measurement of the glass tube element by the light ray extending along a measurement path in a direction of perpendicular to the main extension and tangent to a surface of the shell. The measurement path touches the surface for different measurements at different positions each having a different azimuth angle within a cylindrical coordinate system fixedly attached to the glass tube element and having an origin on a center axis of the glass tube element.

A glass tube element is provided that includes hollow cylindrical section that has a shell enclosing a lumen and a path extending on a surface of the shell facing away from the lumen. The path extends across a first area of the shell where the stress values are within a first interval. The path also extends across a second area of the shell where the stress values are within a second interval.

A glass tube element is provided that includes hollow cylindrical section that has a shell enclosing a lumen and a path extending on a surface of the shell facing away from the lumen. The path extends across a first area of the shell where the stress values are within a first interval. The path also extends across a second area of the shell where the stress values are within a second interval.

A sintered product having: the following chemical analysis, as percentage by mass based on the oxides: Al.sub.2O.sub.3: remainder to 100%, 0.26%≤Na.sub.2O≤4%, 0%≤oxides other than Al.sub.2O.sub.3 and Na.sub.2O≤6%, provided that SiO.sub.2≤2%, the following crystalline phases, as percentages by mass based on the total amount of crystalline phases: 5%≤beta-alumina≤37%, less than 6% of crystalline phases other than beta-alumina and alpha-alumina, remainder to 100%: alpha-alumina.