Feed optimization for the slotted line antenna for high-density plasma production

Ganguli, A.; Baskaran, R.; Pandey, H. D.

doi:10.1109/27.45516

Cited by 19 publications

(19 citation statements)

References 23 publications

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“…For this purpose, the dominant field components of the slow-wave mode of this antenna were determined initially [5]. Subsequently, experiments were performed [6] where different feed structures (auxiliary antennae) were placed within the SLA for exciting different components of the microwave field preferentially. It was expected that when the excited field component corresponded to a dominant field component of the slow-wave mode of the SLA, the excitation of this mode and hence the ensuing plasma production process as well would be most efficient.…”

Section: Introductionmentioning

confidence: 99%

Studies on microwave-induced plasma production using helical slow-wave structures

Ganguli

Naidu

Tewari

1991

IEEE Trans. Plasma Sci.

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This paper presents a detailed study on the optimal use of helical slow-wave structures (both wire and slotted) for plasma production at microwave frequencies. For this purpose a feed optimization study was undertaken in which different feed structures located within the helical coils were used for exciting the helices. Each feed structure excites a preferred component of the wave electric/magnetic field inside the helices. It is seen that the efficacy of plasma production using the different feeds depends directly on the relative importance of the field component (excited by each feed) for the slow-wave mode of the helixloaded waveguide. The best feed for both wire and slotted helices is shown to be a dipole antenna, oriented so as to excite the radial component of the electric field within the antenna. For the wire helices, an axially oriented monopole antenna (which excites an axial electric field) is also shown to yield comparable results. In order to avoid a spontaneous excitation of the dominant fast-wave mode of the helix-loaded waveguide system preferentially, mode-selective structures (resonant or anti-resonant cavities) tuned to the slow-wave mode have been used. The experiments show that the performance of the resonant helical coils is uniformly superior to that of the nonresonant one. The plasma so produced was characterized with respect to the microwave power and magnetic field at the antenna region. A second set of experiments was also performed, where a second helical coil (in addition to the helical antenna being used for plasma production) was used. This helical coil is a long, large diameter, closely wound wire helix which fits snugly into the plasma chamber or the waveguide. Thus the plasma produced by the helical antenna now flows into this long helical transmission line which acts like an extended waveslowing structure. This plasma (surrounded by the long helical line) is characterized once again to study the changes in the plasma parameters induced by this line. It is found that using the long helical transmission line gives some improvement in the plasma density, the bulk electron temperature, and their radial profiles. However, the improvement in the hot and intermediate electron temperatures is seen to be quite significant, which indicates the efficacy of this structure for plasma-heating purposes.

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Section: Introductionmentioning

confidence: 99%

Studies on microwave-induced plasma production using helical slow-wave structures

Ganguli

Naidu

Tewari

1991

IEEE Trans. Plasma Sci.

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“…c, B 1 : externally applied DC magnetic field, m~ mass of electron) of an electron into microwave frequency (w, 1 ) in an externally applied DC magnetic field. The plasma density (n~c) that corresponds to microwave frequency of 2.45 GHz is 7.46 x 10 10 cm-3 • It is found experimentally that the plasma density saturates nearly at n,c and coupling of microwave into plasma does not help for density enhancement [14]. However, a high density plasma can be obtained at off-resonance (we, >> w, 1 ).…”

Section: Singly Charged Ion Sourcesmentioning

confidence: 90%

“…It can be shown that at reson?.nce the wave becomes an electrostatic wave for 6 * 0 [14,16]. Since the phase velocity of the wave is slowed down considerably near resonance (Vphfc < < 1), it is possible for the plasma electrons to interact with the wave when the condition V 11 cos 6 = VPh is obeyed (V 11 -axial velocity of the electrons).…”

Section: Singly Charged Ion Sourcesmentioning

confidence: 98%

Application of Microwaves in Accelerators—A Review

Baskaran¹

1992

IETE Technical Review

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“…[1][2][3] The ECR plasma is produced by matching the cyclotron frequency of an electron in an externally applied direct current ͑dc͒ magnetic field to the microwave frequency and for the ECR plasma heating applications, the microwave is coupled to the R wave ͑electron wave͒ using a special type of antenna. Geller has converted a magnetic mirror machine into an ion source for the production of multiply charged ion beams.…”

Section: Introductionmentioning

confidence: 99%

Experimental studies on a compact electron cyclotron resonance plasma x-ray source

Baskaran

Selvakumaran

1999

Review of Scientific Instruments

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A compact electron cyclotron resonance plasma x-ray source, which has a potential use for medical imaging is presented in this article. In this article, the experimental system and the characterization studies on plasma and x ray are presented. Using a Langmuir probe, the plasma parameters are measured for different magnetic field profiles and gas pressures. The x-ray spectrum is obtained for various gas pressures and magnetic field profiles. In the x-ray spectrum, the Bremstrahlung radiation, peaking at 20–60 keV is observed and the final energy of the x ray is extended up to ∼200 keV. Thermo luminescence dosimeter (CaSO4 sample) is used for estimating the dose at the port and these results are presented for typical x-ray spectra. Using a teletector, the dose at the port for various coil current is measured and these are compared with the estimated dose obtained from the x-ray spectrum.

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Feed optimization for the slotted line antenna for high-density plasma production

Cited by 19 publications

References 23 publications

Studies on microwave-induced plasma production using helical slow-wave structures

Studies on microwave-induced plasma production using helical slow-wave structures

Application of Microwaves in Accelerators—A Review

Experimental studies on a compact electron cyclotron resonance plasma x-ray source

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