ECRIS2010 - Table of Session: TUCOBK (Pulsed Operation)

Paper

Title

Page

Preglow Phenomenon Origins and its Scaling for Ecris

87

I. Izotov, V. Sidorov, V. Skalyga, V. Zorin
IAP/RAS, Nizhny Novgorod, Russia

Preglow effect investigation is one of topical directions of ECR ion sources development at present. Preglow is of interest for efficient short-pulsed multi-charged ion source creation. Particularly, such source of intense beams of short-living radioactive isotopes multi-charged ions is one of key elements in “Beta-Beam” European project [1]. Use of Preglow-generating regime of an ECRIS operation is a promising way of pulsed high-intense multi-charged ion beams production with much shorter edges in comparison with usual operation regime. The first theoretical investigations of Preglow phenomenon were performed in references [2,3]. Present work describes modified model of ECR discharge development in a magnetic trap of the ECRIS as a continuation of [2,3]. Numerical simulations made with the updated model allow authors to propose more physical and intuitive explanation of Preglow phenomenon origins. Obtained dependences of Preglow characteristics on experimental conditions offer a scaling for a wide range of ECRISes.
[1] (ONLINE) http://beta-beam.web.cern.ch/beta-beam/task/diverse/mandate.htm
[2] T. Thuillier et al, Rev. of Sci. Instrum., 79, 02A314, 2008.
[3] I. Izotov et al, IEEE Trans. Plasma Sci. 36, 1494, 2008.

Slides TUCOBK01 [0.928 MB]

TUCOBK02

“Preglow” Investigation in ECR Discharge at 37 GHz, 100 kW

90

V. Skalyga, I. Izotov, S. Razin, V. Sidorov, V. Zorin
IAP/RAS, Nizhny Novgorod, Russia
T. Lamy, T. Thuillier
LPSC, Grenoble, France

Multicharged ion beams generation in "Preglow" regime is now considered as the main way of short pulsed ion source creation for “Beta Beam” project. The "Preglow" effect has been investigated at a several laboratories (LPSC, JYFL, IAP RAS). The effect was discovered at LPSC on PHOENIX ion source using 18 GHz radiation for plasma heating. Investigations at 14 GHz frequency were made at JYFL. Theoretical analysis demonstrated the advantage of MW frequency increase. Theoretical calculations predict possibility of "Preglow" peaks generation with duration about tens microseconds and rather high average ion charge. At present time at LPSC a joint construction of a new generation ECR ion source with 60 GHz gyrotron plasma heating is running. As a continuation of previous research at 14, 18 and 28 GHz at present work results of experimental and theoretical "Preglow" effect investigations at SMIS 37 setup with 37,5 GHz MW plasma heating are reported. Received data are important as fundamental result in physics of ECRISs and at the same time it is the next step on the way of 60 GHz SEISM facility creation. “Preglow” effect was observed and investigated in experiments with ECR discharge stimulated with gyrotron radiation @ 37.5 GHz, 100 kW. Received dependencies of the “Preglow” parameters are in good correspondence with results of numerical simulations. It was shown in experiments that generation of “Preglow” peak with duration about 30 μs is possible.

Slides TUCOBK02 [2.338 MB]

TUCOBK03

Time Evolution of Plasma Potential in Pulsed Operation of ECRIS

93

O.A. Tarvainen, H. A. Koivisto, T. Ropponen, V.A. Toivanen
JYFL, Jyväskylä, Finland
Y. Higurashi, T. Nakagawa
RIKEN Nishina Center, Wako, Japan

The time evolution of plasma potential has been measured in pulsed operation mode with electron cyclotron resonance ion sources at JYFL and RIKEN. Three different ion sources with microwave frequencies ranging from 6.4 to 18 GHz were employed for the experiments. The plasma potential during the preglow and afterglow transients was compared with steady state conditions. The plasma potential was observed to increase 25-75 % during the preglow and 10-30 % during the afterglow. We describe the experimental procedure and present the results of the study in detail.

Slides TUCOBK03 [0.973 MB]

TUCOBK04

Micropulses Generation in ECR Breakdown Stimulated by Gyrotron Radiation at 37.5 GHz

96

V. Skalyga, S. Golubev, I. Izotov, S. Razin, V. Sidorov, A. Vodopyanov, V. Zorin
IAP/RAS, Nizhny Novgorod, Russia

Present work is devoted to experimental and theoretical investigation of possibility of short pulsed (< 100 μs) multicharged ion beams creation. The possibility of quasi-stationary generation of short pulsed beams under conditions of quasi-gasdynamic plasma confinement was shown in recent experiments. Later another way of such beams creation based on “Preglow” effect was proposed. In present work it was demonstrated that in the case when duration of MW pulse is less then formation time of “Preglow” peak, realization of a regime when ion current is equal to zero during MW pulse and intense multicharged ions flux appears only when MW ends could be possible. Such pulses after the end of MW were called "micropulses". In present work generation of micropulses was observed in experiments with ECR discharge stimulated by gyrotron radiation @ 37,5GHz, 100 kW. In this case pulses with duration less than 30 μs. Probably the same effect was observed in GANIL where 14 GHz radiation was used and pulses with duration about 2 ms were registered. In present work it was shown that intensity of such micropulse could be higher than intensity of “Preglow” peak at the same conditions but with longer MW pulse. The generation of micropulses of nitrogen and argon multicharged ions with current of a few mA and length about 30 μs after MW pulse with duration of 30-100 μs was demonstrated. The low level of impurities, high current density and rather high average charge make possible to consider such micropulse regime as perspective way for creation of a short pulsed ion source.

Slides TUCOBK04 [3.473 MB]

Paper	Title	Page
TUCOBK01	Preglow Phenomenon Origins and its Scaling for Ecris	87
	I. Izotov, V. Sidorov, V. Skalyga, V. Zorin IAP/RAS, Nizhny Novgorod, Russia
	Preglow effect investigation is one of topical directions of ECR ion sources development at present. Preglow is of interest for efficient short-pulsed multi-charged ion source creation. Particularly, such source of intense beams of short-living radioactive isotopes multi-charged ions is one of key elements in “Beta-Beam” European project [1]. Use of Preglow-generating regime of an ECRIS operation is a promising way of pulsed high-intense multi-charged ion beams production with much shorter edges in comparison with usual operation regime. The first theoretical investigations of Preglow phenomenon were performed in references [2,3]. Present work describes modified model of ECR discharge development in a magnetic trap of the ECRIS as a continuation of [2,3]. Numerical simulations made with the updated model allow authors to propose more physical and intuitive explanation of Preglow phenomenon origins. Obtained dependences of Preglow characteristics on experimental conditions offer a scaling for a wide range of ECRISes. [1] (ONLINE) http://beta-beam.web.cern.ch/beta-beam/task/diverse/mandate.htm [2] T. Thuillier et al, Rev. of Sci. Instrum., 79, 02A314, 2008. [3] I. Izotov et al, IEEE Trans. Plasma Sci. 36, 1494, 2008.
	Slides TUCOBK01 [0.928 MB]

TUCOBK02	“Preglow” Investigation in ECR Discharge at 37 GHz, 100 kW	90
	V. Skalyga, I. Izotov, S. Razin, V. Sidorov, V. Zorin IAP/RAS, Nizhny Novgorod, Russia T. Lamy, T. Thuillier LPSC, Grenoble, France
	Multicharged ion beams generation in "Preglow" regime is now considered as the main way of short pulsed ion source creation for “Beta Beam” project. The "Preglow" effect has been investigated at a several laboratories (LPSC, JYFL, IAP RAS). The effect was discovered at LPSC on PHOENIX ion source using 18 GHz radiation for plasma heating. Investigations at 14 GHz frequency were made at JYFL. Theoretical analysis demonstrated the advantage of MW frequency increase. Theoretical calculations predict possibility of "Preglow" peaks generation with duration about tens microseconds and rather high average ion charge. At present time at LPSC a joint construction of a new generation ECR ion source with 60 GHz gyrotron plasma heating is running. As a continuation of previous research at 14, 18 and 28 GHz at present work results of experimental and theoretical "Preglow" effect investigations at SMIS 37 setup with 37,5 GHz MW plasma heating are reported. Received data are important as fundamental result in physics of ECRISs and at the same time it is the next step on the way of 60 GHz SEISM facility creation. “Preglow” effect was observed and investigated in experiments with ECR discharge stimulated with gyrotron radiation @ 37.5 GHz, 100 kW. Received dependencies of the “Preglow” parameters are in good correspondence with results of numerical simulations. It was shown in experiments that generation of “Preglow” peak with duration about 30 μs is possible.
	Slides TUCOBK02 [2.338 MB]

TUCOBK03	Time Evolution of Plasma Potential in Pulsed Operation of ECRIS	93
	O.A. Tarvainen, H. A. Koivisto, T. Ropponen, V.A. Toivanen JYFL, Jyväskylä, Finland Y. Higurashi, T. Nakagawa RIKEN Nishina Center, Wako, Japan
	The time evolution of plasma potential has been measured in pulsed operation mode with electron cyclotron resonance ion sources at JYFL and RIKEN. Three different ion sources with microwave frequencies ranging from 6.4 to 18 GHz were employed for the experiments. The plasma potential during the preglow and afterglow transients was compared with steady state conditions. The plasma potential was observed to increase 25-75 % during the preglow and 10-30 % during the afterglow. We describe the experimental procedure and present the results of the study in detail.
	Slides TUCOBK03 [0.973 MB]

TUCOBK04	Micropulses Generation in ECR Breakdown Stimulated by Gyrotron Radiation at 37.5 GHz	96
	V. Skalyga, S. Golubev, I. Izotov, S. Razin, V. Sidorov, A. Vodopyanov, V. Zorin IAP/RAS, Nizhny Novgorod, Russia
	Present work is devoted to experimental and theoretical investigation of possibility of short pulsed (< 100 μs) multicharged ion beams creation. The possibility of quasi-stationary generation of short pulsed beams under conditions of quasi-gasdynamic plasma confinement was shown in recent experiments. Later another way of such beams creation based on “Preglow” effect was proposed. In present work it was demonstrated that in the case when duration of MW pulse is less then formation time of “Preglow” peak, realization of a regime when ion current is equal to zero during MW pulse and intense multicharged ions flux appears only when MW ends could be possible. Such pulses after the end of MW were called "micropulses". In present work generation of micropulses was observed in experiments with ECR discharge stimulated by gyrotron radiation @ 37,5GHz, 100 kW. In this case pulses with duration less than 30 μs. Probably the same effect was observed in GANIL where 14 GHz radiation was used and pulses with duration about 2 ms were registered. In present work it was shown that intensity of such micropulse could be higher than intensity of “Preglow” peak at the same conditions but with longer MW pulse. The generation of micropulses of nitrogen and argon multicharged ions with current of a few mA and length about 30 μs after MW pulse with duration of 30-100 μs was demonstrated. The low level of impurities, high current density and rather high average charge make possible to consider such micropulse regime as perspective way for creation of a short pulsed ion source.
	Slides TUCOBK04 [3.473 MB]