Characteristics of microwave ECR ion thruster powered with plate antenna in cross-magnetic field: Standing wave, skin effect, and mode transition

Fu, S. H.; Ding, Z. F.

doi:10.1063/5.0033067

Cited by 12 publications

(11 citation statements)

References 24 publications

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“…The P W at the second intersecting point also decreases with the increasing gas flow rate. Compared with the 1.6 GHz ECR ion thruster with the cross magnetic field [14], the I b from the 2.45 GHz one exhibits different behaviors in two aspects: (1) I b is a monotonic increasing function of gas flow rate at equal P w ; (2) in the high gas flow regime of 0.3-0.35 sccm, the increasing rate of I b with P w in the third linear curve segment is abnormally larger, being contrary to the low efficiency of ion production in high-P w discharges of conventional ECR ion thrusters [3,[27][28][29][30].…”

Section: Ion Beam Currentmentioning

confidence: 99%

On abnormal behaviors of ion beam extracted from electron cyclotron resonance ion thruster driven by rod antenna in cross magnetic field

Li¹,

Fu²,

Yang³

et al. 2021

Plasma Sci. Technol.

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In a 2.45 GHz electron cyclotron resonance (ECR) ion thruster powered with rod antenna under a cross magnetic field, abnormal behaviours such as sudden drop of ion beam current (I b) and larger increasing-rate of I b in the high microwave power (P w) discharges at high gas flow rates were observed. A differential method was proposed to reveal the changes in the radial profiles of gray values extracted from the end-view discharge images. The increasing-rate of I b with respect to P w was used to evaluate efficiencies of ion production and transport. Analyses indicate that discharges are dominantly sustained by ordinary wave via electron heating in the electron plasma resonance layer that can shift along the rod-antenna, and extraordinary wave can only ignite a discharge in the ECR layer in the low gas flow rate regime. In terms of the confinement region defined by the magnetic field lines intercepting with the screen grid, the confinement region of the optimized 2.45 GHz cross magnetic field takes the shape of hourglass, enabling the high increasing-rate of I b with respect to P w in high power discharges at high gas flow rates. Correlated with the accompanied bright boundary layer appearing in the differentiated image, the sudden drop of I b in the low gas flow rate regime is attributed to the discharge ignited by the enhanced extraordinary wave in the ECR layer neighbouring the narrowest confinement region, where the produced ions can promptly enter the loss region.

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Section: Ion Beam Currentmentioning

confidence: 99%

On abnormal behaviors of ion beam extracted from electron cyclotron resonance ion thruster driven by rod antenna in cross magnetic field

Li¹,

Fu²,

Yang³

et al. 2021

Plasma Sci. Technol.

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“…Due to the high electric field strength in the near-anode region, the power absorption density on the nearest ECR surface is relatively high. Another power absorption peak occurs on the anode side surface, where the electric field features a high component parallel to the magnetic field, leading to O-wave-related discharge Discharge images of the four anode voltage conditions: 0 V, 200 V, 300 V, and 500 V. [34]. standing-wave-induced strong electric field leads to a high electron temperature region near the anode.…”

Section: Thruster Ionization Simulationmentioning

confidence: 99%

Study on the ionization and acceleration of a microwave discharge cusped field thruster

Zhang¹,

Liu²,

Huang³

et al. 2023

J. Phys. D: Appl. Phys.

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The microwave discharge cusped field thruster (MD-CFT) is a novel concept electric micro propulsion device, also a candidate thruster for the gravitational detection mission. A coaxial transmission line resonator (CTLR) is utilized to feed the microwave into the thruster to generate Xe plasma steadily with a mass flow rate as low as 0.1sccm. Due to the separation of ionization and acceleration, the thruster performs high operation mode stability over a wide range of voltage in low mass flow conditions. Experimental and simulation methods are carried out to study the ionization and ion acceleration of the thruster. The results show that in operating conditions with a mass flow rate of 0.1sccm, an anode voltage of 0V to 1000V, and a microwave power of 2W, the right-hand circularly polarized wave (R wave) and the ordinary wave (O wave) play the most important role in the ionization process. The ion acceleration region locates around the exit magnetic separatrix, and the acceleration region tends to converge toward the separatrix as the anode voltage increases, resulting in an increased focus of the thruster plume and concentration of the ion energy distribution. Due to the separation of the ionization and acceleration regions, the thruster performs a divergence efficiency of 0.5-0.8, and an acceleration efficiency of 0.9.

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“…Unlike an ordinary plasma source, the two extraction grids of a gridded ion source act as a simple optical collimator for the optical emission, so that the spatial distribution of the averaged gray values from the pixel array well reproduce the radial profile of discharge glow. If the discharge intensity is defined by n e T e (where n e is electron density and T e is electron temperature), the radial distribution of gray values approximately represents that of the discharge intensity, the reason for which is stated in reference [20].…”

Section: Experimental Apparatusmentioning

confidence: 99%

“…The critical P w at the jump point of I a /I b decreases with the increasing gas flow rate. The jump of I a /I b is correlated with the low-n e region due to the microwave skin effect discussed in reference [20]. In order to quantify the skin effect, the ratio of the gray value in the central region (G c ) to that at the antenna's edge (G e ), i.e., G c /G e , is calculated.…”

Section: Hysteresis and Effect Of Xe Gas Flow Ratementioning

confidence: 99%

“…In order to quantify the skin effect, the ratio of the gray value in the central region (G c ) to that at the antenna's edge (G e ), i.e., G c /G e , is calculated. The calculation procedures are as follows: (1) 7 holes in the central region of the SG and 27 ones along the antenna's edge are selected (see figure 6), aiming to reduce the influence of the asymmetric gas flow field in the discharge chamber and the numerical noise of the camera's pixel array [20]; (2) the red solid circles are also concentric with ion-extraction holes, but have a halved diameter; (3) the gray values averaged over the 7 and 27 red circles are taken as G c and G e , respectively; (4) the procedures from (1) to (3) are repeated for images captured by varying P w at different gas flow rates. The thus-obtained gray-value ratio G c /G e is shown in figure 7.…”

Section: Hysteresis and Effect Of Xe Gas Flow Ratementioning

confidence: 99%

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Effects of secondary γ-electrons from accelerator grid under ion impingement in gridded ion sources

Fu¹,

Tian²,

Ding³

2022

Plasma Sources Sci. Technol.

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Thus far, effects of secondary γ-electrons emitted from accelerator grids of gridded ion sources on ionization in discharge chambers have not been studied. The presence and induced processes of such secondary electrons in a microwave electron cyclotron resonance gridded ion source are confirmed by the consistent explanations of: (1) the observed jump of ion beam current (Ib) in case of a low-density plasma appearing at the chamber’s radial center due to the microwave skin effect; (2) the evolution of glow images recorded from the end-view of the ion source during the jump of Ib; (3) the over-large jump step of Ib with the increasing microwave power; (4) the pattern appearing on the temperature sticker exposed to the discharge operated in the regime where the arrayed energetic-electron beamlets are injected into the discharge chamber; (5) the measured step-increment in the voltage drop across the screen grid sheath. A positive feedback loop composed of involved processes are established to elucidate the underlying mechanism. Energetic γ-electrons from the accelerator grid and warm δ-electrons from the opposite antenna do not produce direct excitation and ionization, but they enhance the electrical confinement of cold electrons by elevating the voltage drop across the sheaths at the antenna and screen grid, thus leading to the jump of Ib. The energetic γ-electrons-based model can be also modified to explain abnormal results observed in the other gridded ion sources. Energetic γ-electrons from accelerator grids should be taken into account in understanding gridded ion sources.

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Characteristics of microwave ECR ion thruster powered with plate antenna in cross-magnetic field: Standing wave, skin effect, and mode transition

Cited by 12 publications

References 24 publications

On abnormal behaviors of ion beam extracted from electron cyclotron resonance ion thruster driven by rod antenna in cross magnetic field

On abnormal behaviors of ion beam extracted from electron cyclotron resonance ion thruster driven by rod antenna in cross magnetic field

Study on the ionization and acceleration of a microwave discharge cusped field thruster

Effects of secondary γ-electrons from accelerator grid under ion impingement in gridded ion sources

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