Previous experimental investigations, carried out at Alta/Centrospazio in collaboration with Consorzio RFX, on magnetic and electrostatic fluctuations in gas-fed MPD thrusters (both self and applied field), have shown that gross magnetohydrodynamic instabilities develop whenever the current rises beyond a threshold value. These instabilities have m/n = 1/1 azimuthal and axial periodicity and are interpreted in terms of helical kink modes. The paper deals with experimental observations relating the kink mode amplitude, measured by a set of magnetic coils, to the main discharge parameters. In particular, it is shown that a significant decrease in the applied voltage driving the discharge with no significant variation of thrust is observed when these instabilities are suppressed. The suppression has been obtained by means of a passive system (patent pending), consisting in an insulating plate, axially inserted into the discharge chamber of the thruster. The plate divides the discharge chamber in two halves and interrupts the helical currents produced by the kink, effectively stabilizing the kink itself.
Performance Improvement Due to Kink Instability Suppression in MPD Thruster
PAGANUCCI, FABRIZIO;ANDRENUCCI, MARIANO
2005-01-01
Abstract
Previous experimental investigations, carried out at Alta/Centrospazio in collaboration with Consorzio RFX, on magnetic and electrostatic fluctuations in gas-fed MPD thrusters (both self and applied field), have shown that gross magnetohydrodynamic instabilities develop whenever the current rises beyond a threshold value. These instabilities have m/n = 1/1 azimuthal and axial periodicity and are interpreted in terms of helical kink modes. The paper deals with experimental observations relating the kink mode amplitude, measured by a set of magnetic coils, to the main discharge parameters. In particular, it is shown that a significant decrease in the applied voltage driving the discharge with no significant variation of thrust is observed when these instabilities are suppressed. The suppression has been obtained by means of a passive system (patent pending), consisting in an insulating plate, axially inserted into the discharge chamber of the thruster. The plate divides the discharge chamber in two halves and interrupts the helical currents produced by the kink, effectively stabilizing the kink itself.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
