Physics-Based Circuit Model for a Water-Wall High-Temperature Arc Lamp Using Finite Volume Method
High-temperature arc lamps are used for thermal processing of semiconductor wafers. A vortex water wall on the inner surface of the lamp's enclosure is used to provide cooling for the glass. It has been experimentally observed that, above certain levels of injected energy, the arc shows an unstable behavior and is self-extinguished. In this paper, a physics-based model for the water-wall high-temperature arc lamp is derived and implemented in the form of an equivalent electrical circuit. The equivalent circuit is then coupled to the flash power supply equivalent circuit to validate the derived model against experimental voltage and current waveforms.
Experimental results for a pulsed vortex water wall high-pressure argon lamp
This paper presents experimental results for a pulsed vortex water wall high pressure arc lamp. The power source consists of a DC ignitor connected in series with a sustaining source. The ignitor is shorted after a sustaining current is achieved, followed by the connection of a regulated pulsed current source connected in parallel with the sustaining source. The application of this lamp in rapid thermal processing systems dictates that the interpulse period of the pulsed source be made as short as possible. Experiments have been performed with and without the sustaining source. Arc overvoltage after the current is reapplied becomes larger as the interpulse period is made longer. Overvoltages are higher if no sustaining source is used during the interpulse period. An acoustic resonance is observed with a duration equal to the axial convective transit time. A sustaining source may not be required based on the results of the experiments.
CLINICAL TRIALS OF THE ABDOMINAL LEFT VENTRICULAR ASSIST DEVICE (ALVAD): PROGRESS REPORT.
An abdominal left ventricular assist device (ALVAD) is undergoing controlled clinical trials in our institution. The ALVAD is pneumatically-actuated, synchronously or asynchronously with an external console and is interposed between the apex of the left ventricle and the infrarenal abdominal aorta. It is an order of magnitude more effective than conventional intraaortic balloon pumping. Thus far, we have implanted this pump in 21 patients (15 males and six females). The average age has been 50. The duration of cardiopulmonary bypass with intensive pharmacologic support and IABP until ALVAD implantation has been nearly 4 hours. The plasma hemoglobins prior to ALVAD implantation have averaged 168 mg%. The platelet counts at implantation have averaged 68,000 mm(3). The average duration of ALVAD support has been in excess of one day and the longest trial extended for one week. We have been able to remove the pump after ventricular recovery in two instances and effected cardiac allografting in one instance of ALVAD dependency. We have found that (1) the profoundly depressed left (and right) ventricles can recover if totally supported with this device; (2) the device can function in the presence of ventricular fibrillation and/or standstill; (3) the device can effectively replace both left and right ventricular function in the presence of normal pulmonary vascular resistance and microcirculatory hemodynamics; and (4) in the presence of impending multiple organ failure, procrastination in use is to be avoided.