The Ifp Temperature Control System
C. Mangene · 1985
The Internal Picket Fence (IPF) is made of a set of proportional wire tube chambers which sit inside the outer vacuum vessel of the 15' Bubble Chamber. Though they are covered with layers of super-insulation, they are partially exposed to the cryogenic system of the Bubble Chamber and the Bubble Chamber magnet. The chambers are, therefore, equipped with heaters designed to maintain them at a reasonable temperature. As the operating conditions of the bubble chamber are changed, particularly during warm-up and cool-down, it is necessary to control the power to the heaters dynamically. Due to the adverse conditions in the area and the number of chambers (96 cans), we decided to operate the heaters remotely with a computer control system. The IPF Temperature Control System consists of five basic sub-systems. A STD bus Z80 microprocessor system, a serial communication link, a temperature monitor, a heater controller and heater driver card. The separate sub-systems are described. Each chamber has a 4-wire platinum resistor (RTD, R = 100 ohms at 0'C) and a 220 ohm resistance wire heater for temperature readback and control.