It is found that the screen grid transparency increases with the acceleration voltage and decreases with the beam current, while the accelerator grid current ratio and divergence loss decrease first and then increase with the beam current.
The variation of the screen grid transparency, the accelerator grid current ratio and the divergence loss were explored.
Since the 1970s several thrust vectoring systems have been developed, with the translatable accelerator grid electrode being considered the most promising.
Simulation results also show that Kr ion thrusters have more advantages than Xe ion thrusters, such as higher screen grid transparency, smaller accelerator grid current ratio, larger cut-off current threshold, and better divergence loss characteristic.
During Beam operation breakdowns will occur across the accelerator grids and Source components causing transient high voltages between parts normally at low voltages, so stressing the electrical insulation of sensor cables, connectors and feedthroughs.
As the design for such cooling systems presents some technological and heat transfer issues, a specific R&D program has been carried out, particularly referred to the accelerator grids that are among the most critical components.
This paper focuses a preliminary feasibility study of integration of SINGAP accelerator grids into the support structure of a MAMuG type accelerator; the review or design of new electrostatic shields to improve the voltage withstanding capability of the system and the preliminary design of electrical and hydraulic connections routing from the bushing to the accelerator are also discussed.
The ceramic insulators are critical elements, both from the structural and electrical point of view, of the 1 MV electrostatic accelerator of the MITICA injector, as they are required to sustain both the mechanical loads due to the cantilevered weight of the ion source and the high electric field between the accelerator grids.
The company JEMA has designed and manufactured two High Voltage Switching Mode Power Supplies (HVSMPS), rated at 130 kV dc and 130 A, each of which will feed the accelerator grids of two Positive Ion Neutral Injector (PINI) loads, to be installed at the Joint European Torus (EFDA-JET facility located at Culham, UK).
The project, called Multi-design Innovative Cooling Research & Optimization (MICRO), aims, on one hand, to verify the present solution applied inside the NBI accelerator grids (i.e. MITICA experiment) and, on the other, to perform further improvements in the heat transfer process with an acceptable pressure drop and reliable manufacturing process.
A long pulse acceleration of high-power-density hydrogen negative ion beams of 184 MeVm2 (0.97 MeV, 190 A/m2) has been successfully achieved up to a facility limit of 60 s by using a 5 stage multi-aperture multi-grid accelerator, which is the first demonstration of the ITER relevant beam with a pulse length over the time constant of cooling capability of the water-cooled acceleration grids.
