| Paper | Title | Other Keywords | Page |
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| MOOBMH03 | Frequency Tuning Effect On The Bremsstrahlung Spectra, Beam Intensity And Shape In An ECR Ion Source | ECR, electron, plasma, ion | 15 |
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The effect of the frequency tuning on bremsstrahlung spectra, beam intensity and shape in the 10 GHz, Nanogan ECR ion source have been investigated. The main aim of this work was to study the effect on a lower frequency type of ECR source where the separation between various modes in the cavity is much larger. The warm and cold components of the electrons were observed to be directly correlated with the beam intensity enhancement in the case of Ar9+ but not so for O5+. However, the warm electron component was much smaller than the cold component. The beam shapes of O5+ measured as a function of frequency showed a strong variation without hollow beam formation. Due to the use of an octupole magnetic structure in the Nanogan ECR source, the quadrupolar structure of the ECR surface is modified with the frequency tuning. In general, we have observed a strong absorption of microwave power at various frequencies whenever the reflection co-efficient showed a minimum value and the effect was seen stronger for the higher charge states. Details of the measurements carried out on the bremsstrahlung spectra, beam intensity and shape are presented together with the results of simulations.
* Effect of frequency tuning on bremsstrahlung spectra, beam intensity, and shape in the 10 GHz NANOGAN electron cyclotron resonance ion source, Rev. Sci.Instrum. 85,02A944 (2014) |
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Slides MOOBMH03 [23.075 MB] | ||
| WEOBMH03 | Investigation on the Origin of High Energy X-Rays Observed in 3rd Generation ECRIS | ECR, electron, ion, ion-source | 127 |
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| The operation of third generation ECR ion source heated with 24 or 28 GHz microwave frequency shows a high energy x-ray spectrum with a characteristic temperature much higher than the one observed at the usual heating frequencies (14-18 GHz). The behaviour of the x-ray spectrum is studied based on the review of a set of data previously done at LBNL [1]. The data reviewed shows that the hot x-ray temperature scales with the ECR frequency. The experimental data is compared with the prediction of a simple model of ECR heating developed for this purpose. A formula to estimate the ECR resonance thickness is calculated. The model explains nicely the experimental x-ray temperature variation when the central magnetic field of the ECRIS is changed. It demonstrates that such a magnetic field variation does not change the electron confinement time and that the change of the x-ray spectrum temperature is due to the change of the ECR zone thickness. The only way for the model to reproduce the fact that the x-ray temperature scales with the ECR frequency is to assume that the electron confinement time scales (at least) with the ECR frequency. This result brings new credit to the theoretical prediction that the hot electron RF scattering is decreasing when the ECR frequency increases.[2,3] The spatial gyrac effect, which can be considered as another possible origin of the very hot x-ray produced in ECRIS is recalled for convenience in this paper. | |||
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Slides WEOBMH03 [1.214 MB] | ||