AUTOMATIC FLUORINE CONTROL SYSTEM

摘要

PROBLEM TO BE SOLVED: To control fluorine concentration in a laser chamber accurately by providing a fluorine monitor for monitoring the fluorine concentration and feeding a signal back to an automatic control system in order to operate a laser in a sweet spot. SOLUTION: A voltmeter 38 monitors the charge voltage of a high voltage source 36 and provides a signal to a feedback control circuit 40 delivering a control signal to a low flow control valve 42 in order to increase/decrease the continuous fluorine injection rate from a gas bottle 44 when it is required for sustaining a high voltage within a narrow desired range. Fluorine concentration is measured at an interval of about 8 hours by a fluorine monitor. A pressure regulator 46 sustains the pressure in a chamber 20 at 3 atm by feeding a releasing gas into a fluorine monitor tank 48 being sustained sequentially at 2 atm through a pressure regulator 50 thus sustaining a substantially constant fluorine concentration.