A study of three-half-turn and frame antennae for ion cyclotron range of frequency plasma heating in the URAGAN-3M torsatron

Lysoǐvan, A. I.; Moiseenko, V. E.; Plyusnin, Victor F.; Kasilov, Sergei; Bondarenko, V.N.; Chechkin, V. V.; Fomin, I.P.; Григорьева, Л.И.; Konovalov, V.G.; Koval'ov, S.V.; Litvinov, A.P.; Mironov, Yu.K.; Nazarov, N.I.; Pavlichenko, O. S.; Pavlichenko, R. O.; Shapoval, A. N.; Skibenko, A. I.; Волков, Е. Д.

doi:10.1016/0920-3796(94)00185-a

Cited by 11 publications

(15 citation statements)

References 8 publications

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“…[10]) is a result of balance of the benefit to have a compact antenna which occupies one device port and the necessity to suppress the excitation of low-k || Alfvén resonances that reside at the plasma periphery and cause plasma edge heating. Experiments with the threehalf-turn (THT) antenna were attempted earlier [11,12]. They showed an increase in plasma density from ne ≈ (0.5-2) × 10 12 cm −3 provided by the preceding pulse of the frame antenna to ne ≈ (0.5-1.5) × 10 13 cm −3 [11].…”

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confidence: 99%

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RF plasma production and heating below ion-cyclotron frequencies in Uragan torsatrons

Moiseenko¹,

Berezhnyj²,

Bondarenko³

et al. 2011

Nucl. Fusion

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In the IPP-Kharkiv there are two torsatrons (stellarators) in operation, and in both of them Alfvén resonance heating under high-k ∥ conditions is used. This method of heating is advantageous for small-size devices, since in contrast to the minority and second-harmonic heating it can be realized at lower plasma densities. A series of experiments has been performed at the Uragan-3M torsatron with an aim to investigate the features of the discharge with a three-half-turn antenna. Electron temperatures in the range are achieved at plasma densities . The plasma energy content has increased by a factor of 2 with respect to the plasma produced with the frame antenna. A new four-strap shielded antenna has been manufactured and installed in the Uragan-2M. A high-frequency discharge for wall conditioning is introduced in the Uragan-2M torsatron. The discharge is sustained by a specially designed small frame antenna, and efficient hydrogen dissociation is achieved. A self-consistent model has been developed for simulation of plasma production in ICRF. The model includes a set of particle and energy-balance equations for the electrons, and the boundary problem for the Maxwell equations. The first calculation results on RF plasma production in the Uragan-2M stellarator with the frame-type antenna are presented.

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confidence: 99%

“…Experiments with the threehalf-turn (THT) antenna were attempted earlier [11,12]. They showed an increase in plasma density from ne ≈ (0.5-2) × 10 12 cm −3 provided by the preceding pulse of the frame antenna to ne ≈ (0.5-1.5) × 10 13 cm −3 [11]. At that time the Uragan-3M was not equipped with a diagnostics for measuring the electron temperature.…”

mentioning

confidence: 99%

RF plasma production and heating below ion-cyclotron frequencies in Uragan torsatrons

Moiseenko¹,

Berezhnyj²,

Bondarenko³

et al. 2011

Nucl. Fusion

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“…Different mechanisms of U-3M heating were considered before [8,9], which might be important for the selection of a discharge scenario. It should be pointed out that only in a narrow magnetic field region from 0.68 to 0.72 T were the plasma discharges under our consideration produced in the U-3M torsatron [10,11]; in the case of a fixed RF frequency, consequently, the heating conditions are strongly resonant ( ω/ω ≈ 5%) in contrast to the predictions [1][2][3].…”

Section: Introductionmentioning

confidence: 89%

“…Alfvén wave heating is considered to be responsible for RF heating [1][2][3] in the U-3M torsatron (l = 3, m = 9, R 0 = 1 m, ā ≈ 0.12 m, B 0 1 T) in the frequency range ω/ω c ≈ 0.8 (where ω c is the ion cyclotron frequency at the plasma center). It exploits the slow wave (SW) direct or indirect generation and its dissipation on electrons [4,5].…”

Section: Introductionmentioning

confidence: 99%

U-3M ion energy distribution measurements during frame antenna plasma production and heating in the ICRF range

Dreval

Slavnyj

2011

Plasma Phys. Control. Fusion

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An energy sweeping technique is developed and applied for charge exchange (CX) neutral particle diagnostics in the URAGAN-3M (U-3M) torsatron. Measurements are performed during low-density (n e = (0.5-1) × 10 12 cm −3 ) frame antenna radio frequency (RF) plasma discharges in the RF frequency range close to the ion cyclotron frequency (ICRF). The presence of ions with energies up to 4 keV is established experimentally. According to the experimental data the ion energy distribution is close to Maxwellian in the energy range 0.4-2.5 keV and can be described by the ion temperature T i = 300-600 eV. This is an indication of direct RF energy deposition onto the ions due to the negligible ion-electron energy exchange. The radial dependences of CX neutral flux and ion temperature under consideration are investigated using a set of similar discharges. The radial distribution of the studied temperature has a flat profile in the range ρ = 0.5-1. This is an indication of the ion energy deposition localization close to the plasma edge. The possible mechanisms of ion heating are briefly discussed.

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“…In ICP sources, a planar spiral coil [10,11] has been used due to its relatively simple geometry, and the addition of an external magnetic field has led to better plasma performance [12][13][14][15]. As for the nuclear fusion field, in stellarators, plasma production studies have been performed in the ion cyclotron range of frequencies (ICRF) using slot and three half-turn antennae located outside the chamber [16][17][18]. More recently, ICRF plasma production for the purpose of wall conditioning, preionization and plasma sustainment has been performed in stellarators and tokamaks using the conventional loop antennae located inside the chamber [19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Trials of RF plasma production using different antenna geometries with magnetic field

Shinohara

Soejima

1998

Plasma Phys. Control. Fusion

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Plasma production studies excited by the radio frequency (RF) wave were carried out using various antenna configurations. Six types of side antennae, located outside the large cylindrical chamber, and two types of internal loop antennae were tested. The ion saturation current I is of a probe and the plasma emission were measured as a function of the filling pressure, the RF power and the magnetic field. With the increase in the power and the magnetic field, I is increased in most cases, while some of the antennae showed the maximum I is values under low magnetic field. Among the side antennae, a spiral antenna produced the highest value of I is in a wide operational window. For the case of the internal loop antennae, the electric field parallel to the magnetic field did not show a significant contribution to plasma production. These results suggest the importance of the loop-like RF-induced electric field. When an external magnetic field was applied, the uniformity of the plasma produced by the internal loop antennae in both the radial and axial directions was improved.

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A study of three-half-turn and frame antennae for ion cyclotron range of frequency plasma heating in the URAGAN-3M torsatron

Cited by 11 publications

References 8 publications

RF plasma production and heating below ion-cyclotron frequencies in Uragan torsatrons

RF plasma production and heating below ion-cyclotron frequencies in Uragan torsatrons

U-3M ion energy distribution measurements during frame antenna plasma production and heating in the ICRF range

Trials of RF plasma production using different antenna geometries with magnetic field

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