Abstract: Chemical vapor deposition apparatus has a quartz envelope supporting a resistance heater. A boron nitride pill box configured core supports resistance heater windings. The core has a base having a cylindrical upper portion defining a hollow chamber and an upper annular ring. A circular top includes an upper circular portion and lower circular portion mating with the base. The annular ring surface is in thermal contact with the upper circular portion to transfer heat from the annular ring to the circular top. A zirconia insulator cups the core, providing heat insulation, in conjunction with a heat shield coating in the quartz envelope interior. Arrays of quartz envelope heaters provide for mass production of semiconductors. A horizontal configuration includes a laminar flow head and disposed at an angle to the horizontal.