Features of radio frequency surface plasma sources with a solenoidal magnetic field

• Operation of Radio Frequency surface plasma sources (RF SPS) with a solenoidal magnetic field are described. • RF SPS with solenoidal and saddle antennas are discussed. • Preliminary dependences of beam current and extraction current on RF power, gas flow, solenoidal magnetic field and filter magnetic field are presented. Efficiency of plasma generation in a Radio Frequency (RF) ion source can be increased by application of a solenoidal magnetic field. The specific efficiency of positive ion generation was improved by the solenoidal magnetic field, from 5 mA/cm2 kW to 200 mA/cm2 kW. Chen presented an explanation for the concentration of plasma density near the axis by a magnetic field through a short circuit in the plasma plate [ D. Curreli and F. Chen, Equilibrium theory of cylindrical discharges with special application to helicons, PHYSICS OF PLASMAS, 18, 113501 (2011). ]. Additional concentration factor can be a secondary ionelectron emission initiated by high positive potential of plasma relative the plasma plate. Secondary negative ion emission can be increased by cesiation-injection of cesium, increasing a secondary electron and photo emission. RF SPS with a solenoidal magnetic field was tested at SNS test stand with ELEBT The RF ion source consists of an AlN ceramic chamber with a cooling jacket from keep. At the left side, an RF assisted triggering plasma gun (TPG) is attached. At the right side, a plasma electrode with an extraction system is attached. The discharge chamber is surrounded by a saddle (or solenoidal) antenna. .The LEBT at the right side consists of an accelerator electrode and two electrostatic lenses which focus a beam into a 7.5 mm diameter hole in the chopper target. Lant=4.3 mcH Start discharge at 2 MHz, at Prf=15%, =293 mV, P=3.8 kW; Iant=120 A. U=6.5 kV. At 13.56 MHz discharge start At P=0.5 kW, Iant=14 A, U=1.2 kV. Q=24 sccm.

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