Characterization of a high-intensity unipolar-mode pulsed ion source with improved magnetically insulated diode

Abstract

A magnetically insulated ion diode (MID) with an improved external-magnetic field system has been developed and installed onto a TEMP-6-type high-intensity pulsed ion source in order to produce a high-intensity pulsed ion beam (HIPIB) for surface modification of materials. The external-magnetic field MID is operated in unipolar mode based on dielectric high-voltage flashover, and a double coaxial pulse-forming line (PFL) powered with a Marx generator is used to form the unipolar pulse of nanosecond width. A specially designed cathode has been constructed with a forked connection to two symmetrically installed transformers to improve the effect of the magnetic field and thus increase the stability of generation and propagation of the ion beam. It was found that the efficient generation of HIPIB mainly depended on the magnetic field strength, the gas pressures in reverse and output switches of PFL, and the anode–cathode (A–K) gap of the external-magnetic field MID. A proper magnetic field strength was found with magnetic field power system at dc charging voltage of 8 kV. The proper A–K gap distance is not uniform with the value varied from 6 to 8 mm. Suitable gas pressures for reverse and output switches were about 1.2 and 2.4 atm, respectively, at a charging voltage of 40 kV to the Marx generator. The most efficient plasma generation and ion extraction led to a maximum output of HIPIB with a peak ion current density of 300 A cm−2 and a beam pulse width of 80 ns (full width at half maximum), at an accelerating pulse of 300–350 kV with a pulse width of 70 ns.

Changes in surface morphology of Ti6Al4V alloy and ZrO2-Y2O3 ceramic coating modified by high-intensity pulsed ion beams

“…The structure and operation details of this apparatus have been reported previously [8,9]: for the surface modification of the Ti6Al4V alloy, a magnetically insulated diode (MID) with self-magnetic field was used as the ion source; and a MID with external-magnetic field that can produce an ion beam of a higher intensity used for the treatment of the ceramic coating. The parameters of ion beams are listed in Table 1 Surface morphology of samples was observed using a JSM-5600LV scanning electron microscope (SEM) before and after the ion beam irradiation.…”

Investigation of the characteristics of an intense ion beam propagated outside the diode

“…Geometric focusing has been realized in the intense ion diodes of different types [1][2][3][4][5][6] for the formation and transportation of ion beams. This allows increasing the densities of the current and energy of the ion beam in the focus area by several times.…”

A study of an external-magnetic insulated ion beam diode with the No. 25 transformer oil anode

“…For a total ion beam energy of (80-90) J per pulse, 500 J additional energy is required to generate the magnetic field [5]. With its high stability and high efficiency (20-40)%, the external magnetic insulated diode [6,7] is widely applied in scientific researches.…”