The influence of ambipolarity on plasma confinement and on the performance of electron cyclotron resonance ion sources

Schächter, Levi; Dobrescu, S.; Stiebing, K. E.; Thuillier, T.; Lamy, T.

doi:10.1063/1.2801679

Cited by 6 publications

(3 citation statements)

References 7 publications

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“…The MD method is based on two complementary effects, first a partial restoration of the plasma ambipolarity which leads to a general increase in the confinement for all charge states 6 and second a strong increase in the plasma electron density by the overcompensation of plasma losses by cold secondary electrons emitted from the MD structures with high secondary electron emission coefficients. This increase in plasma density again results in a better confinement and hence reduced emission of bremsstrahlung radiation, in agreement with an experiment, where we demonstrated that in a MD source the same output of highly charged ions can be obtained at distinctly reduced microwave power compared to the reference source.…”

Section: Results and Commentsmentioning

confidence: 99%

Influence of the electron cyclotron resonance plasma confinement on reducing the bremsstrahlung production of an electron cyclotron resonance ion source with metal-dielectric structures

Schächter¹,

Stiebing

Dobrescu³

2009

Review of Scientific Instruments

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The influence of metal-dielectric (MD) layers (MD structures) inserted into the plasma chamber of an electron cyclotron resonance ion source (ECRIS) onto the production of electron bremsstrahlung radiation has been studied in a series of dedicated experiments at the 14 GHz ECRIS of the Institut für Kernphysik der Universität Frankfurt. The IKF-ECRIS was equipped with a MD liner, covering the inner walls of the plasma chamber, and a MD electrode, covering the plasma-facing side of the extraction electrode. On the basis of similar extracted currents of highly charged ions, significantly reduced yields of bremsstrahlung radiation for the "MD source" as compared to the standard (stainless steel) source have been measured and can be explained by the significantly better plasma confinement in a MD source as compared to an "all stainless steel" ECRIS.

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Section: Results and Commentsmentioning

confidence: 99%

Influence of the electron cyclotron resonance plasma confinement on reducing the bremsstrahlung production of an electron cyclotron resonance ion source with metal-dielectric structures

Schächter¹,

Stiebing

Dobrescu³

2009

Review of Scientific Instruments

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“…A related example of “thermal” field‐aligned plasma currents may be the “short‐circuit” effect first discussed by Simon [] in magnetically confined laboratory plasmas, in which cross‐field thermal ion diffusion, e.g., to the axial walls of a conductive containment vessel [ Zhilinskii and Tsendin , ], can induce field‐aligned electron eddy currents which short across field lines at the end walls [ Drentje et al ., ]. The competition of these currents with electron ambipolar diffusion has been the focus of recent theoretical discussion [ Fruchtman , ] and simulation studies [ Lafleur and Boswell , ], and thermally driven electron shorting currents turn out to be a significant design consideration for electron cyclotron ion sources [ Schachter et al ., ]. Analogous phenomena are common in other areas of physics as well.…”

Section: Current System Wave Modes and Physical Requirementsmentioning

confidence: 99%

Surface current balance and thermoelectric whistler wings at airless astrophysical bodies: Cassini at Rhea

et al. 2014

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Sharp magnetic perturbations found by the Cassini spacecraft at the edge of the Rhea flux tube are consistent with field-aligned flux tube currents. The current system results from the difference of ion and electron gyroradii and the requirement to balance currents on the sharp Rhea surface. Differential-type hybrid codes that solve for ion velocity and magnetic field have an intrinsic difficulty modeling the plasma absorber's sharp surface. We overcome this problem by instead using integral equations to solve for ion and electron currents and obtain agreement with the magnetic perturbations at Rhea's flux tube edge. An analysis of the plasma dispersion relations and Cassini data reveals that field-guided whistler waves initiated by (1) the electron velocity anisotropy in the flux tube and (2) interaction with surface sheath electrostatic waves on topographic scales may facilitate propagation of the current system to large distances from Rhea. Current systems like those at Rhea should occur generally, for plasma absorbers of any size such as spacecraft or planetary bodies, in a wide range of space plasma environments. Motion through the plasma is not essential since the current system is thermodynamic in origin, excited by heat flow into the object. The requirements are a difference of ion and electron gyroradii and a sharp surface, i.e., without a significant thick atmosphere.Key PointsSurface current balance condition yields a current system at astronomical bodiesCurrent system possible for sharp (airless) objects of any sizeCurrent system is thermoelectric and motion through the plasma nonessential

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“…The commissioning will continue at 18 GHz for 3 to 6 months with noble gases and eventually a metallic ion mentioned in the list above. A special dielectric layer adapted to A-PHOENIX will be tested in collaboration with NIPNE, 10 and its influence on the high charge state production in the 1 kW microwave range will be explored. Next, the first inox plasma chamber will be changed to the second model boosting the radial field to 1.8 T. The same investigations will then be done at 18 and 28 GHz.…”

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First plasma of the A-PHOENIX electron cyclotron resonance ion source

Thuillier

Lamy

Latrasse

et al. 2008

Review of Scientific Instruments

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A-PHOENIX is a new compact hybrid electron cyclotron resonance ion source using a large permanent magnet hexapole (1.92 T at the magnet surface) and high temperature superconducting Solenoids (3 T) to make min- B structure suitable for 28 GHz cw operation. The final assembly of the source was achieved at the end of June 2007. The first plasma of A-PHOENIX at 18 GHz was done on the 16th of August, 2007. The technological specificities of A-PHOENIX are presented. The large hexapole built is presented and experimental magnetic measurements show that it is nominal with respect to simulation. A fake plasma chamber prototype including thin iron inserts showed that the predicted radial magnetic confinement can be fulfilled up to 2.15 T at the plasma chamber wall. Scheduled planning of experiments until the end of 2008 is presented.

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The influence of ambipolarity on plasma confinement and on the performance of electron cyclotron resonance ion sources

Cited by 6 publications

References 7 publications

Influence of the electron cyclotron resonance plasma confinement on reducing the bremsstrahlung production of an electron cyclotron resonance ion source with metal-dielectric structures

Influence of the electron cyclotron resonance plasma confinement on reducing the bremsstrahlung production of an electron cyclotron resonance ion source with metal-dielectric structures

Surface current balance and thermoelectric whistler wings at airless astrophysical bodies: Cassini at Rhea

First plasma of the A-PHOENIX electron cyclotron resonance ion source

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