Caneses, Juan FranciscoBlackwell, Boyd D.Corr, Cormac2026-01-012026-01-019781622769810https://hdl.handle.net/1885/733799285RF magnetic fluctuation probes and symmetric double Langmuir probes have been utilized to characterize Argon helicon plasma in a converging magnetic field. We observe that when enough RF power is supplied an Ar II blue core mode is formed suggestive of the presence of fast electrons (∼30 eV) ([1], [2]). Results indicate a linear increase in the plasma density in the direction of increasing magnetic field. During high power operation (2.1 kW) the plasma density reaches a peak near the maximum gradient of the converging magnetic field, the helicon's phase velocity matches the electron thermal velocity and its wavelength becomes half the antenna size. Radial wavefield measurements during the blue core suggest the presence of an m = +1 second radial mode.4en201284876942040