Preliminary Results Session #1
| The volume type ion source is known to deliver a stable beam with low emittance. In the first session the longetivity of the filament was tested at low power. The source was tuned to produce a 1.2 mA He+ beam. The following source parameters were chosen: After initial filament conditioning the arc discharge and beam extraction was started on Thursday 15/04/2010 at 1.50 pm. The online monitoring of ion beam current and residual gas pressure was made available since Friday 15/04/2010 at 1.00 pm. |
 |
|
Figure 1 shows the beam current measured at beam dump downstream of the LEBT. The graph shows the beam current and the residual gas preasure as a function of time. The SCL #1 was mached for a moderate power deposition at the beam dump. Secondary electron suppressor was not used. Thus these measurements only served as a way to ensure proper functioning of the ion source. The interuption of beam current was due to HV power supply failure caused by sparking. It was assumed that filament aging is influenced by sputtering effects inside the plasma generator. The resistance of the filament is then expected to increase due to decrease in filament thickness and increase in specific resistance as a function of temperature. |
 |
|
Figure 2 shows the resistance of the filament as a function of time. The resistance was recorded manually over large interval of time. First seven houers denotes the baking procedure (1). Arc discharge and beam extraction were started right after the conditioning (2). Filament was found broken after 235 h (3) and the experiment was stopped. Results: The life time was approximately 230 h for the given source parameter without any automatic control of the ion source. First experiences with a reliability test and data acquisition system were very fruitful. Seven interuptions because of sparking were observed druing the test and will be subjected to the improvement of the extraction system and the monitoring of the ion source parameters. |