Crystal growers are used to for heating galium arsinide, synthetic rubies, and other crystalin materials in a zirconium or platinum crucible to 950° and higher. The primary use of crystal growers is the pulling of galium arsenide crystals for the laser and IC industries. A crystal grower is designed to have a very accurate control system to maintain temperature within ±3°C for a period of up to 6 weeks continous. Any variance greater than this is the difference between a good crystal and a bad one. Pillar has been suppling equipment for this application since 1981. We developed our first design as part of the Crystal Grower line as a 50 kW 10 kHz Crystal Grower. These have been a secessful and popular line for us. We then developed in 1985 a 30 kW 10Khz Crystal Grower for smaller growth applications.The application required the following additions to the basic system.

• Precision Power Control Circuitry
• Coil Current Control
• UPS or Autostart for Control Circuitry
• Coil Current Feedback
• 4 to 20 mA Control
• Secialized Output Configuration
• Line Monitor Circuitry
• Integral Heat Station