ECRIS-2014 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
MOOBMH01	Periodic Beam Burrent Oscillations Driven By Electron Cyclotron Instabilities In ECRIS Plasmas	plasma, ion, cyclotron, ECRIS	5
	O.A. Tarvainen, T. Kalvas, H. A. Koivisto, J.P.O. Komppula, R.J. Kronholm, J.P. Laulainen JYFL, Jyväskylä, Finland I. Izotov, D. Mansfeld, V. Skalyga IAP/RAS, Nizhny Novgorod, Russia V. Toivanen CERN, Geneva, Switzerland
	Experimental observation of cyclotron instabilities in electron cyclotron resonance ion source plasma operated in cw-mode is reported. The instabilities are associated with strong microwave emission and a burst of energetic electrons escaping the plasma, and explain the periodic oscillations of the extracted beam currents. The instabilities are shown to restrict the parameter space available for the optimization of high charge state ion currents.
	Slides MOOBMH01 [2.020 MB]

MOOBMH03	Frequency Tuning Effect On The Bremsstrahlung Spectra, Beam Intensity And Shape In An ECR Ion Source	ECR, cavity, plasma, ion	15
	G.O. Rodrigues, D. Kanjilal, N. Kumar, K. Mal, Y. Mathur IUAC, New Delhi, India A. Roy VECC, Kolkata, India
	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)
	Slides MOOBMH03 [23.075 MB]

MOOBMH04	Emission Spectroscopy Diagnostic of Plasma Inside 2.45 GHz ECR Ion Source at PKU	plasma, ion, ion-source, ECR	20
	Y. Xu, J. Chen, J.E. Chen, Z.Y. Guo, S.X. Peng, H.T. Ren, J.F. Zhang, T. Zhang, J. Zhao PKU, Beijing, People's Republic of China A.L. Zhang Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
	Funding: This work is supported by the National Science Foundation of China (Grant Nos. 11175009 and 91126004). The 2.45 GHz permanent magnet electron cyclotron resonance ion source (PMECR) at Peking University (PKU) can produce 100 mA H⁺, 40 mA H²⁺ and 20 mA H³⁺ under different conditions, but the physics processes and plasma characteristics within the discharge chamber are not very clear until now. Langmuir probe, laser detachment, absorption spectroscopy and optical emission spectroscopy are common approaches for diagnosing the plasma. Among those methods, optical emission spectroscopy is a simple in situ one without disturbing the plasma. To better understand the plasma producing processes, a new ion source with transparent quartz discharge chamber was designed at PKU so that plasma diagnostic can be performed through directly detecting the light generated within ECR zone by fiber optics. Collisional radiative (CR) model is utilized to calculate plasma parameters like electron density ne and electron temperature Te for non-equilibrium plasma in ECR ion source. The spectroscopy diagnosis platform has been constructed, and preliminary results will be presented in this paper. *Author to whom correspondence should be addressed. Electronic mail: sxpeng@pku.edu.cn.
	Slides MOOBMH04 [2.330 MB]

MOOAMH05	Combination of Two ECRIS Calculations: Plasma Electrons and Extracted Ions	ion, plasma, emittance, simulation	38
	S. Biri, R. Rácz ATOMKI, Debrecen, Hungary R. Lang, J. Mäder, F. Maimone, B.R. Schlei, P. Spädtke, K. Tinschert GSI, Darmstadt, Germany
	In strongly magnetized ECRIS plasmas collisions do not influence the path of the charged particle. Electrons and ions can move more freely only along the magnetic field line compared to the transverse direction. Extraction simulation requires that the trajectories of charged particles have to be traced through the plasma chamber. In previous simulations the particle density at the beginning of the trajectory deep inside the plasma has been unknown. Now the full 3D electron tracking within the plasma chamber has been combined with the generation of initial ion starting conditions including particle density for ion tracking. The TrapCAD code has been used to determine the electron spatial distribution in a certain energy window. The idea is that at the places where the electron reaches a specific energy, an ion trajectory can be started. The magnetic field has been modeled with OPERA. The computer code KOBRA3-INP has been used for ray tracing. First results will be discussed and compared with experimental experience. The number of affecting parameters on the operating conditions of the ion source may lead to a multi-dimensional optimization space for simulation.
	Slides MOOAMH05 [10.655 MB]

WEOMMH04	Thermal Design of Refridgerated Hexapole 18 GHz ECRIS HIISI	plasma, simulation, ECRIS, permanent-magnet	114
	T. Kalvas, H. A. Koivisto, K. Ranttila, O.A. Tarvainen JYFL, Jyväskylä, Finland
	A project is underway for constructing a new 18 GHz ECR ion source HIISI at University of Jyväskylä. An innovative plasma chamber structure with grooves at magnetic poles is being studied. This allows large chamber radius at the poles, which is relevant for the performance of the ion source while smaller radius between the poles makes space for chamber water cooling. The hexapole will be refridgerated to sub-zero temperatures to boost the coercivity and the remanence of the permanent magnet material. The hexapole structure is insulated from high temperature solenoid coils and plasma chamber by vacuum. The thermal design of the structure has been made using a thermal diffusion code taking in account radiative, conductive and convective heat transfer processes. The heat flux from plasma has been estimated using electron trajectory simulations with sensitivity analysis on the electron energy distribution. The electron simulations are verified by comparing to experimental data from 14 GHz ECR. The electron and thermodynamic simulation efforts are presented together with an analysis of the H-field vs. coersivity in the permanent magnets.
	Slides WEOMMH04 [5.163 MB]

WEOBMH03	Investigation on the Origin of High Energy X-Rays Observed in 3rd Generation ECRIS	ECR, cavity, ion, ion-source	127
	T. Thuillier LPSC, Grenoble Cedex, France
	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.
	Slides WEOBMH03 [1.214 MB]

Paper

Title

Other Keywords

Page

MOOBMH01

Periodic Beam Burrent Oscillations Driven By Electron Cyclotron Instabilities In ECRIS Plasmas

plasma, ion, cyclotron, ECRIS

5

O.A. Tarvainen, T. Kalvas, H. A. Koivisto, J.P.O. Komppula, R.J. Kronholm, J.P. Laulainen
JYFL, Jyväskylä, Finland
I. Izotov, D. Mansfeld, V. Skalyga
IAP/RAS, Nizhny Novgorod, Russia
V. Toivanen
CERN, Geneva, Switzerland

Experimental observation of cyclotron instabilities in electron cyclotron resonance ion source plasma operated in cw-mode is reported. The instabilities are associated with strong microwave emission and a burst of energetic electrons escaping the plasma, and explain the periodic oscillations of the extracted beam currents. The instabilities are shown to restrict the parameter space available for the optimization of high charge state ion currents.

Slides MOOBMH01 [2.020 MB]

MOOBMH03

Frequency Tuning Effect On The Bremsstrahlung Spectra, Beam Intensity And Shape In An ECR Ion Source

ECR, cavity, plasma, ion

15

G.O. Rodrigues, D. Kanjilal, N. Kumar, K. Mal, Y. Mathur
IUAC, New Delhi, India
A. Roy
VECC, Kolkata, India

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)

Slides MOOBMH03 [23.075 MB]

MOOBMH04

Emission Spectroscopy Diagnostic of Plasma Inside 2.45 GHz ECR Ion Source at PKU

plasma, ion, ion-source, ECR

20

Y. Xu, J. Chen, J.E. Chen, Z.Y. Guo, S.X. Peng, H.T. Ren, J.F. Zhang, T. Zhang, J. Zhao
PKU, Beijing, People's Republic of China
A.L. Zhang
Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China

Funding: This work is supported by the National Science Foundation of China (Grant Nos. 11175009 and 91126004).
The 2.45 GHz permanent magnet electron cyclotron resonance ion source (PMECR) at Peking University (PKU) can produce 100 mA H⁺, 40 mA H²⁺ and 20 mA H³⁺ under different conditions, but the physics processes and plasma characteristics within the discharge chamber are not very clear until now. Langmuir probe, laser detachment, absorption spectroscopy and optical emission spectroscopy are common approaches for diagnosing the plasma. Among those methods, optical emission spectroscopy is a simple in situ one without disturbing the plasma. To better understand the plasma producing processes, a new ion source with transparent quartz discharge chamber was designed at PKU so that plasma diagnostic can be performed through directly detecting the light generated within ECR zone by fiber optics. Collisional radiative (CR) model is utilized to calculate plasma parameters like electron density ne and electron temperature Te for non-equilibrium plasma in ECR ion source. The spectroscopy diagnosis platform has been constructed, and preliminary results will be presented in this paper.
*Author to whom correspondence should be addressed. Electronic mail:
sxpeng@pku.edu.cn.

Slides MOOBMH04 [2.330 MB]

MOOAMH05

Combination of Two ECRIS Calculations: Plasma Electrons and Extracted Ions

ion, plasma, emittance, simulation

38

S. Biri, R. Rácz
ATOMKI, Debrecen, Hungary
R. Lang, J. Mäder, F. Maimone, B.R. Schlei, P. Spädtke, K. Tinschert
GSI, Darmstadt, Germany

In strongly magnetized ECRIS plasmas collisions do not influence the path of the charged particle. Electrons and ions can move more freely only along the magnetic field line compared to the transverse direction. Extraction simulation requires that the trajectories of charged particles have to be traced through the plasma chamber. In previous simulations the particle density at the beginning of the trajectory deep inside the plasma has been unknown. Now the full 3D electron tracking within the plasma chamber has been combined with the generation of initial ion starting conditions including particle density for ion tracking. The TrapCAD code has been used to determine the electron spatial distribution in a certain energy window. The idea is that at the places where the electron reaches a specific energy, an ion trajectory can be started. The magnetic field has been modeled with OPERA. The computer code KOBRA3-INP has been used for ray tracing. First results will be discussed and compared with experimental experience. The number of affecting parameters on the operating conditions of the ion source may lead to a multi-dimensional optimization space for simulation.

Slides MOOAMH05 [10.655 MB]

WEOMMH04

Thermal Design of Refridgerated Hexapole 18 GHz ECRIS HIISI

plasma, simulation, ECRIS, permanent-magnet

114

T. Kalvas, H. A. Koivisto, K. Ranttila, O.A. Tarvainen
JYFL, Jyväskylä, Finland

A project is underway for constructing a new 18 GHz ECR ion source HIISI at University of Jyväskylä. An innovative plasma chamber structure with grooves at magnetic poles is being studied. This allows large chamber radius at the poles, which is relevant for the performance of the ion source while smaller radius between the poles makes space for chamber water cooling. The hexapole will be refridgerated to sub-zero temperatures to boost the coercivity and the remanence of the permanent magnet material. The hexapole structure is insulated from high temperature solenoid coils and plasma chamber by vacuum. The thermal design of the structure has been made using a thermal diffusion code taking in account radiative, conductive and convective heat transfer processes. The heat flux from plasma has been estimated using electron trajectory simulations with sensitivity analysis on the electron energy distribution. The electron simulations are verified by comparing to experimental data from 14 GHz ECR. The electron and thermodynamic simulation efforts are presented together with an analysis of the H-field vs. coersivity in the permanent magnets.

Slides WEOMMH04 [5.163 MB]

WEOBMH03

Investigation on the Origin of High Energy X-Rays Observed in 3rd Generation ECRIS

ECR, cavity, ion, ion-source

127

T. Thuillier
LPSC, Grenoble Cedex, France

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.

Slides WEOBMH03 [1.214 MB]