PERFORMANCE OF A COLD-GAS JET AT SHORT PULSE LENGTHS CALCULATION OF THE MINIMUM PULSE RATE AND MEASUREMENT OF THE SPECIFIC IMPULSE FOR PULSES SHORTER THAN 20MS

摘要

Mass-ejection devices are a means of stabilising a synchronous satellite and usually take the form of gas jets. A method has now been devised by which an analog computer can be used to determine the gas jet pulse rate as a function of the impulse per pulse during limit cycling in the presence of a variable disturbance torque. Results show that there is a pulse length yielding a minimum pulse rate and that it is within the capabilities of solenoid valves now available.nAs no experimental results on the specific impulses of very short pulses were to hand, a test facility was built for measuring the specific impulses associated with gas-jet pulses shorter than 20 ms. It has been found that a well-designed valve-nozzle unit still yields the steady-state specific impulse at a pulse length of 10 ms and that the losses do not exceed 10% at an open time of 3 ms. The gas used was nitrogen at ambient temperature. The smallest gas pressure was 1 bar.