Permanent-magnet helicon sources and arrays: A new type of rf plasma

Chen, Francis F.; Torreblanca, H.

doi:10.1063/1.3089287

Cited by 35 publications

(17 citation statements)

References 14 publications

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“…A number of other researchers have noted a correlation between the wave phase velocities and certain significant electron velocities 5,6,10 ͑such as the velocity of electrons giving a peak in the ionization rate͒, which could lead to wave-particle interactions. 10 Low field helicons are particularly attractive for plasma processing 13,14 or space propulsion applications, 15 where the small field needed reduces the required equipment and system hardware, while also having significantly lower power requirements ͑since the power consumption in any solenoids is proportional to B 0 2 ͒ or none at all if permanent magnets are used. While some work has been done on these low field helicons in nonuniform magnetic fields, 7,15 the majority of work has typically focused on uniform fields.…”

Section: Introductionmentioning

confidence: 99%

Plasma control by modification of helicon wave propagation in low magnetic fields

Lafleur¹,

Charles²,

Boswell³

2010

Physics of Plasmas

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By making use of nonuniform magnetic fields, it is shown experimentally that control of helicon wave propagation can be achieved in a low pressure ͑0.08 Pa͒ expanding plasma. The m = 1 helicon waves are formed during a direct capacitive to wave mode transition that occurs in a low diverging magnetic field ͑B 0 Ͻ 3 mT͒. In this initial configuration, waves are prevented from reaching the downstream region, but slight modifications to the magnetic field allows the axial distance over which waves can propagate to be controlled. By changing the effective propagation distance in this way, significant modification of the density and plasma potential profiles can be achieved, showing that the rf power deposition can be spatially controlled as well. Critical to the modification of the wave propagation behavior is the magnetic field strength ͑and geometry͒ near the exit of the plasma source region, which gives electron cyclotron frequencies close to the wave frequency of 13.56 MHz.

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Section: Introductionmentioning

confidence: 99%

Plasma control by modification of helicon wave propagation in low magnetic fields

Lafleur¹,

Charles²,

Boswell³

2010

Physics of Plasmas

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“…Details on the inductance limit are given in Ref. 3. Note that the quartz tube is flared out into a "skirt" at the bottom.…”

Section: Apparatusmentioning

confidence: 99%

“…This effect causes a useful increase in density occurring at a density that depends on the magnetic field and the length of the discharge tube. An array of eight small tubes, built several years ago 3 , successfully produced plasmas of density in the 10 11 cm -3 range, uniform over 56 cm width. This experiment demonstrated that a simple, inexpensive helicon arrays can cover large substrates with uniform plasma for roll-to-roll processing.…”

Section: Introductionmentioning

confidence: 99%

Performance of a permanent-magnet helicon source at 27 and 13 MHz

Chen

2012

Physics of Plasmas

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A small helicon source is used to create dense plasma and inject it into a large chamber. A permanent magnet is used for the dc magnetic field (B-field), making the system very simple and compact. Though theory predicts that better antenna coupling will occur at 27.12 MHz, it was found that 13.56 MHz surprisingly gives even higher density due to practical effects not included in theory. Complete density n and electron temperature Te profiles are measured at three distances below the source. The plasma inside the source is also measured with a special probe, even under the antenna. The density there is lower than expected because the plasma created is immediately ejected, filling the experimental chamber. The advantage of helicons over inductively coupled plasmas (with no B-field) increases with RF power. At high B-fields, edge ionization by the Trivelpiece-Gould mode can be seen. These results are useful for design of multiple-tube, large-area helicon sources for plasma etching and deposition because problems are encountered which cannot be foreseen by theory alone.

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“…A proof of principle that an array of multiple sources can produce an uniform plasma has already been carried out in Argon 6 . The investigation of Helicon coupling in hydrogen and deuterium discharges is being carried out at a small laboratory setup (see Fig 4).…”

Section: Helicon Dischargementioning

confidence: 99%

Ways to improve the efficiency and reliability of radio frequency driven negative ion sources for fusion

Kraus

Briefi

Fantz

et al. 2013

Review of Scientific Instruments

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Large RF driven negative hydrogen ion sources are being developed at IPP Garching for the future NBI system of ITER. The overall power efficiency of these sources is low, because for the RF power supply self-excited generators are utilized and the plasma is generated in small cylindrical sources ("drivers") and expands into the source main volume. At IPP experiments to reduce the primary power and the RF power required for the plasma production are performed in two ways: The oscillator generator of the prototype source has been replaced by a transistorized RF transmitter and two alternative driver concepts, a spiral coil, in which the field is concentrated by ferrites, which omits the losses by plasma expansion and a helicon source are being tested.

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Permanent-magnet helicon sources and arrays: A new type of rf plasma

Cited by 35 publications

References 14 publications

Plasma control by modification of helicon wave propagation in low magnetic fields

Plasma control by modification of helicon wave propagation in low magnetic fields

Performance of a permanent-magnet helicon source at 27 and 13 MHz

Ways to improve the efficiency and reliability of radio frequency driven negative ion sources for fusion

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