| Autor: |
Mark D. Carter, Leonard D. Cassady, Edgar A. Bering, Franklin R. Chang Díaz, Benjamin W. Longmier, Jared P. Squire, Tim W. Glover, Chris S. Olsen, Maxwell G. Ballenger, Andrew V. Ilin, Greg McCaskill |
| Rok vydání: |
2012 |
| Předmět: |
|
| Zdroj: |
48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit. |
| DOI: |
10.2514/6.2012-3930 |
| Popis: |
Testing of the VX-200 engine was performed over a wide throttle range in a vacuum facility with sufficient volume and pumping to permit exhaust plume measurements at low background pressures and sufficiently large charge exchange mean free paths. Experimental results are presented with the VX-200 engine installed in a 150 m 3 vacuum chamber with an operating pressure below 1x10 -3 Pa (1x10 -5 Torr), and with an exhaust plume diagnostic measurement range of 5 m in the axial direction and 1 m in the radial directions. Measurements of plasma flux, RF power, and neutral gas flow rate, combined with knowledge of the kinetic energy of the ions leaving the VX-200 engine, are used to determine the ionization cost of argon and krypton in the first stage helicon plasma discharges. Experimental data on ionization cost, ion fraction, exhaust plume expansion angle, thruster efficiency, and total force are presented that characterize the VX-200 engine performance over a wide throttling range from 15 kW to 200 kW total RF power. A semi-empirical model of the thruster efficiency as a function of specific impulse was developed to fit the experimental data, and reveals a second stage Ion Cyclotron Heating (ICH) RF power coupling efficiency of 85%. Operation at an RF power level of 200 kW yields a thruster efficiency of 72%±9% at a specific impulse of 4900±300 s. A high thrust-to-power operating mode was characterized over a wide parameter space with a maximum thrust to power ratio of 51 mN/kW at a specific impulse of 1660 s for a ratio of ICH RF power to helicon RF power of 0.7:1. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
