TY - JOUR
T1 - High-current-density gas ion ribbon beam formation
AU - Ryabchikov, Alexander I.
AU - Sivin, Denis O.
AU - Korneva, Olga S.
AU - Lopatin, Ilya V.
AU - Ananin, Peter S.
AU - Prokopenko, Nikita A.
AU - Akhmadeev, Yuri Kh
PY - 2018/10/21
Y1 - 2018/10/21
N2 - Experimental results are presented to demonstrate the possibility of forming extended repetitively pulsed low-energy gaseous ion beams with a notably high current density. The symbiosis of plasma-immersion extraction of ions and their subsequent ballistic focusing in the semi-cylindrical geometry of the focusing system was first used to form a high-density nitrogen and argon ion ribbon beam. The gas-discharge plasma was formed using a hot-cathode-arc discharge-based modified extended source. A nitrogen and argon ion beam was steadily formed at bias potentials of an amplitude up to 1000 V and a pulse duration of 2–80μs at a pulse frequency of 103-104 pulses/s. In the experiments, an inverse change in current amplitude of the focused ion beam was observed with respect to the initial nitrogen and argon plasma densities. The change in the current ratio formed by the nitrogen and argon ion beams in comparison with the initial plasma density is associated with the effect of the ion atomic mass on a high-voltage sheath formation near the grid electrode and the ratio of the sheath width and grid cell dimensions. An argon ion beam with a current of 0.35 A and a nitrogen ion beam with a current of 0.6 A at a focused ribbon beam length of 23 cm were obtained by installing a grid focusing system in the form of a partial cylindrical surface (radius 7.5 cm) at 35 cm from the gas-discharge plasma generator output. A decrease in distance to 20 cm ensured an increase in argon ion current to 0.8 A and nitrogen ion current to 1.3 A. The maximum ion current density at a distance that corresponded to the cylindrical grid radius for nitrogen and argon ions exceeded 0.08 A/cm2 and 0.05 A/cm2, respectively.
AB - Experimental results are presented to demonstrate the possibility of forming extended repetitively pulsed low-energy gaseous ion beams with a notably high current density. The symbiosis of plasma-immersion extraction of ions and their subsequent ballistic focusing in the semi-cylindrical geometry of the focusing system was first used to form a high-density nitrogen and argon ion ribbon beam. The gas-discharge plasma was formed using a hot-cathode-arc discharge-based modified extended source. A nitrogen and argon ion beam was steadily formed at bias potentials of an amplitude up to 1000 V and a pulse duration of 2–80μs at a pulse frequency of 103-104 pulses/s. In the experiments, an inverse change in current amplitude of the focused ion beam was observed with respect to the initial nitrogen and argon plasma densities. The change in the current ratio formed by the nitrogen and argon ion beams in comparison with the initial plasma density is associated with the effect of the ion atomic mass on a high-voltage sheath formation near the grid electrode and the ratio of the sheath width and grid cell dimensions. An argon ion beam with a current of 0.35 A and a nitrogen ion beam with a current of 0.6 A at a focused ribbon beam length of 23 cm were obtained by installing a grid focusing system in the form of a partial cylindrical surface (radius 7.5 cm) at 35 cm from the gas-discharge plasma generator output. A decrease in distance to 20 cm ensured an increase in argon ion current to 0.8 A and nitrogen ion current to 1.3 A. The maximum ion current density at a distance that corresponded to the cylindrical grid radius for nitrogen and argon ions exceeded 0.08 A/cm2 and 0.05 A/cm2, respectively.
KW - Ballistic focusing
KW - Ions of gas
KW - Plasma
KW - Plasma-immersion extraction
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U2 - 10.1016/j.nima.2018.07.088
DO - 10.1016/j.nima.2018.07.088
M3 - Article
AN - SCOPUS:85051405939
VL - 906
SP - 56
EP - 60
JO - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
SN - 0168-9002
ER -