Identification of the ECR zone in the SWISSCASE ECR ion source

Bodendorfer, Michael; Altwegg, Kathrin; Würz, Peter; Shea, Herbert

doi:10.1016/j.nimb.2008.07.019

Cited by 4 publications

(4 citation statements)

References 9 publications

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“…Both of them slow down the upstream shifting of the EPR layer. The reason for this is that, in the case of magnetic confinement, the large electron's Larmor radius and the high electron-neutral collision frequency at the high electron temperature are factors promoting electron transport across magnetic field lines [37]. When ions gain more energy in collision with hightemperature electrons, ion transport across magnetic field is also raised.…”

Section: Exact Location Of Gas Breakdown In Ecr Layermentioning

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: Exact Location Of Gas Breakdown In Ecr Layermentioning

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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“…The anisotropic behavior of the plasma bulk electron temperature even in the overdense plasma signifies the ECR heating [31,32]. With further increase of time after the MW launch, i.e., near t = 2000 ns, the plasma bulk temperature (T e )is decreased to $10-12 eV.…”

Section: Time Evolution Of Plasma With Power Depositionmentioning

confidence: 99%

“…This range lies close to the thermal electron temperature. Therefore, the reduction of the high energy component of the plasma bulk temperature can be argued as the minimal occurrence of ECR heating process and correspondingly the initiation of the electrostatic heating mechanisms in the same time frame [29][30][31]33]. The plasma reaches steady state after 2000 ns (2 μs) (Figure 7a).…”

Section: Time Evolution Of Plasma With Power Depositionmentioning

confidence: 99%

Evolution of Microwave Electric Field on Power Coupling to Plasma during Ignition Phase

Mallick¹,

Bandyopadhyay²,

Kumar³

2020

Selected Topics in Plasma Physics

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During the gas ignition process, the plasma and the microwave electric fields are evolved with time together in the plasma volume. The spatio-temporal evolution pattern of microwave-radiated plasma parameters is reported here, highlighting the role of these electric fields on power coupling processes. Evolutions of electric field and so power coupling processes are calculated using the finite element method (FEM). It is observed that the main power coupling mechanism is electron cyclotron resonance (ECR) method; however, with the evolution of plasma, the mode shifts from ECR to off-ECR-type heating with time. Off-ECR heating in the form of upper hybrid resonance (UHR) method, electrostatic (ES) ion acoustic wave heating method is important heating mechanisms during highly dense plasma condition, when density is above critical density for launched frequency, 2.45 GHz. The conclusions on the shifting of heating mechanisms are also drawn based on the 3D maps of spatio-temporal plasma density and hot electron temperature evolution.

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“…The charge state distribution of an ion source critically depends on its design parameters, especially the magnetic confinement field and the excitation frequency. Consequently, the choice of a permanent magnetic confinement asks for a precise planning and design [3] before the production process due to very limited possibilities of field manipulation after the production of the magnetic confinement system. This paper presents a numerical simulation of the argon charge state distribution inside the MEFISTO ECR ion source and allows us to simulate future ECR sources before production, thereby significantly improving a successful ion source realization with the desired charge state distribution.…”

Section: Introductionmentioning

confidence: 99%

Global plasma simulation of charge state distribution inside a 2.45 GHz ECR plasma with experimental verification

Bodendorfer

Würz²,

Hohl

2010

Plasma Sources Sci. Technol.

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For the first time, the charge state distribution inside the MEsskammer für FlugzeitInStrumente und Time-Of-Flight (MEFISTO) electron cyclotron resonance (ECR) plasma and in the extracted ion beam was successfully simulated. A self-consistent ECR plasma ionization model (Hohl M 2002 MEFISTO II: Design, setup, characterization and operation of an improved calibration facility for solar plasma instrumentation PhD Thesis University of Bern) was further developed, recomputing the ion confinement time for every ion species and in every time step based on the actual plasma potential rather than using a prescribed constant ion confinement time. The simulation starts with a user defined set of initial conditions and develops the problem in time space by an adaptive step length fourth order Runge-Kutta (RK4) solver, considering particle densities based on ionization rates, recombination rates, ion confinement times and plasma potential. At the simulation end, a steady-state ion charge state distribution is reached, which is in excellent agreement with the measured ion beam charge state distribution of the MEFISTO ion source for Ar 1+ to Ar 5+ and in good agreement for Ar 6+ .

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Identification of the ECR zone in the SWISSCASE ECR ion source

Cited by 4 publications

References 9 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

Evolution of Microwave Electric Field on Power Coupling to Plasma during Ignition Phase

Global plasma simulation of charge state distribution inside a 2.45 GHz ECR plasma with experimental verification

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