Control of antenna coupling in high-density plasma production by m=0 helicon waves

Sakawa, Y.; Takino, T.; Shoji, T.

doi:10.1063/1.122232

Cited by 16 publications

(11 citation statements)

References 15 publications

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“…We see two discharge modes in Ar; one is the LD mode, in which the discharge is sustained by an antenna induction field at low P rf (р0.4 kW); the other is the HD mode, in which plasmas are produced by helicon waves at high P rf (у0.5 kW͒; in between the two modes, n p jumps by more than an order-of-magnitude. 17,20 The density-jump is also observed in Xe and He. In Xe, n p is unstable and shows two levels within 5 ms of the pulse length at the vicinity of the densityjump, which is shown in Fig.…”

Section: ͑8͒mentioning

confidence: 70%

“…Two single-loop antennas ͑width of each antennaϭ1.5 cm, separationϭ10 cm͒, which are connected in series with the phase between the two being zero ͑0°antenna͒, are used to excite the mϭ0 azimuthal helicon mode. 20 Measurements are conducted at tϭ4.5 ms, where t ϭ0 corresponds to the time when the rf current is applied. A static magnetic field of B 0 р1.4 kG at the plasma center is generated in the axial direction via five magnetic coils and three power supplies.…”

Section: ͑8͒mentioning

confidence: 99%

“…Very few experimental investigations were conducted to find an optimum B 0 in helicon wave discharges using molecular gases such as H 2 and N 2 . 14 In this article, we investigate the contribution of the SW on high-density plasma production by mϭ0 helicon waves 14,[16][17][18][19][20] using several gases such as H 2 , D 2 , He, N 2 , Ne, Ar, and Xe.…”

Section: Introductionmentioning

confidence: 99%

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Contribution of slow waves on production of high-density plasmas by m=0 helicon waves

1999

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Towards a better comprehension of plasma formation and heating in high performances electron cyclotron resonance ion sources (invited) Rev. Sci. Instrum. 83, 02A336 (2012) Commissioning of heating neutral beams for COMPASS-D tokamak Rev. Sci. Instrum. 83, 02B114 (2012) Development of a versatile multiaperture negative ion source Rev. Sci. Instrum. 83, 02A707 (2012) Plasma dynamics in microsecond megaampere plasma opening switchesThe contribution of the slow waves ͑SWs͒ on high-density plasma production by mϭ0 helicon waves is investigated in H 2 , D 2 , He, N 2 , Ne, Ar, and Xe plasmas. The density-jump is observed in all the gases used at optimum external magnetic fields B 0 . The measured plasma density n p as a function of B 0 peaks at a condition close to the lower-hybrid resonance in H 2 , D 2 , He, N 2 , and Ne, whereas, the measured dispersion relation indicates the excitation of helicon wave. Dispersion relation of electromagnetic waves is solved using dielectric tensor elements of a cold uniform plasma including ion terms, which shows two branches: the SW and fast ͑helicon͒ wave. The transition from the ionization by SWs, which are excited in the low-density plasma produced by an antenna induction field, to that by helicon waves has been predicted to explain the mechanism to produce the high-density plasma in the helicon wave discharges.

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Section: ͑8͒mentioning

confidence: 70%

Section: ͑8͒mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Contribution of slow waves on production of high-density plasmas by m=0 helicon waves

1999

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“…For reasons which will become clear, our design uses m = 0 antennas. The behavior of such antennas has also been studied by numerous authors [35][36][37] .…”

Section: Methodsmentioning

confidence: 99%

Permanent Magnet Helicon Source for Ion Propulsion

Chen

2008

IEEE Trans. Plasma Sci.

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Helicon sources have been proposed by at least two groups for generating ions for space propulsion: the HDLT concept at the Australian National University (ANU), and the VASIMR concept at the Johnson Space Center in Houston. These sources normally require a large electromagnet and power supply to produce the magnetic field. At this stage of research, emphasis has been on the plasma density and ion current that can be produced, but not much on the weight, size, impulse, and gas efficiency of the thruster. This paper concerns the source itself and shows that great savings in size and weight can be obtained by using specially designed permanent magnets (PMs). This PM helicon design, originally developed for plasma processing of large substrates, is extended here for ion thrusters of both the HDLT and VASIMR types. Measured downstream densities are of order 10 12 cm -3 , which should yield much higher ion currents than reported so far. The design principles have been checked experimentally, showing that the predictions of the theory and computations are reliable. The details of two new designs are given here to serve as examples to stimulate further research on the use of such sources as thrusters.

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“…In order to develop a compact, high-density plasma source of L λ z , where L is the plasma length and λ z is the axial wavelength of the helicon wave, we have been studying plasma production using an m = 0 azimuthal mode [3][4][5][6][7] of standing helicon waves (SHWs). Excitation of SHWs has been reported by several reseachers.…”

Section: Introductionmentioning

confidence: 99%

Plasma Production by m=0 Standing Helicon Waves

Nisoa

Sakawa

Shoji

2000

Jpn. J. Appl. Phys.

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m = 0 standing helicon waves (SHWs) are used to produce high-density Ar plasmas, of the order of 10 13 cm −3 , in a bounded cylindrical plasma column. Axial mode number N = 1, 3, and 5 (N is the number of half-wavelengths in the plasma column) SHWs are strongly excited for plasma length L = 10-26 cm with the rf power P rf ≤ 3.5 kW and external static magnetic field B 0 = 237 G. Hollow and parabolic density profiles that depend on the axial mode of SHW are observed. The standing wave ratio decreases with L, and travelling helicon waves dominate the plasma production for L > 26 cm. The measured results are compared with a two-dimensional wave calculation.

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Control of antenna coupling in high-density plasma production by m=0 helicon waves

Cited by 16 publications

References 15 publications

Contribution of slow waves on production of high-density plasmas by m=0 helicon waves

Contribution of slow waves on production of high-density plasmas by m=0 helicon waves

Permanent Magnet Helicon Source for Ion Propulsion

Plasma Production by m=0 Standing Helicon Waves

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