ECRIS2012 - List of Keywords (detector)

Paper	Title	Other Keywords	Page
TUPP01	Quantitative Determination of ¹⁴⁶Sm/¹⁴⁷Sm Ratios by Accelerator Mass Spectrometry with an ECR Ion Source and Linear Acceleration for ¹⁴⁶Sm Half-Life Measurement	ion, ECR, ion-source, target	43
	N. Kinoshita UTTAC, Tsukuba, Ibaraki, Japan P. Collon, Y. Kashiv, D. Robertson, C.J. Schmitt, X.D. Tang University of Notre Dame, Indiana, USA C. Deibel MSU, East Lansing, Michigan, USA C. Deibel, B. DiGiovine, J.P. Greene, D. Henderson, C.L. Jiang, S.T. Marley, R.C. Pardo, E. Rehm, R.H. Scott, R.C. Vondrasek ANL, Argonne, USA T. Nakanishi, A. Yokoyama Kanazawa University, Kanazawa, Japan M. Paul The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel
	Funding: Supported by U.S. DOE, Office of Nuclear Physics, contract No. DE-AC02-06CH11357, NSF JINA Grant Nr. PHY0822648 and Science Research Prog. of Japan Society for the Promotion of Science (20740161) The alpha-decaying ¹⁴⁶Sm nuclide is used for chronology of the Solar System and silicate mantle differentiation in planets. We performed a new determination of 146Sm half-life by measuring ¹⁴⁶Sm/¹⁴⁷Sm alpha activity and atom ratios in ¹⁴⁷Sm activated via (g,n), (n,2n) and (p,2n) reactions and obtained a value (68 Myr), smaller than that adopted so far (103 Myr), with important geochemical implications. The experiment required determination of ¹⁴⁶Sm/¹⁴⁷Sm ratios by high-energy (6 MeV/u) accelerator mass spectrometry to discriminate ¹⁴⁶Sm from isobaric ¹⁴⁶Nd contaminant. Activated Sm targets were dissolved, chemically purified and reconverted to metallic Sm. Sputter cathodes, made by pressing the Sm metal into high-purity Al holders, were used to feed the Argonne ECR ion source. ¹⁴⁶Sm²²⁺, ¹⁴⁷Sm²²⁺ ions were alternately injected and accelerated with the ATLAS linac by proper scaling of ion source and accelerator components. A tightly-fitted quartz cylindrical liner was inserted in the ECR plasma chamber to reduce contamination from the walls. ¹⁴⁶Sm ions were eventually counted in a gas-filled magnet and ¹⁴⁷Sm ions either measured as charge current or counted after proper attenuation. N. Kinoshita et al., Science 334, 1614 (2012)

TUPP17	Installation and Operation of a 28 GHz Gyrotron for the RIKEN Superconducting ECR Ion Source	cathode, ion, ion-source, power-supply	71
	J. Ohnishi, Y. Higurashi, T. Nakagawa RIKEN Nishina Center, Wako, Japan
	The RIKEN 28-GHz ECRIS uses a gyrotron microwave source fabricated by Mitsubishi Electric Corporation. The maximum output power is 10 kW. The gyrotron produces TE02-mode microwaves, which are converted into the TE01 mode by a mode converter. In the first test on the gyrotron performed using a dummy load, we observed the 50-300 Hz ripples of ~500 W in the output power of 1-7 kW, and it was difficult to make a stable operation in the low-power. These ripples were reduced to one-tenth by stabilizing the cathode voltage and then the gyrotron could produce microwaves from < 0.5 kW stably. The operation of the ion source with the 28 GHz gyrotron was started in 2011 and the ion source supplied U and Xe beams to the RIBF for two months. The power of the microwaves fluctuated slowly in the range of 870-1250 W, which influenced the beam current from the ion source. This fluctuation was caused by a slight change of the current of the solenoid of the gyrotron depending on the room temperature. We replaced the power supply with new one which has a current stability of 10ppm per day, and stabilized the microwave power in the range of 5% in the operation of 2 kW successfully.

WEPP03	Plasma Instability in the Afterglow of ECR Discharge Sustained in a Mirror Trap	electron, plasma, ion, ECR	125
	I. Izotov, A. Mansfeld, V. Skalyga, V. Zorin IAP/RAS, Nizhny Novgorod, Russia T. Grahn, T. Kalvas, H. A. Koivisto, J.P.O. Komppula, P. Peura, O.A. Tarvainen, V. Toivanen JYFL, Jyväskylä, Finland
	Funding: Work was performed in frame of realization of federal targeted program "Scientific and pedagogical labor force for an innovative Russia" for 2009-2013 yy. A number of studies have been devoted to the investigations of plasma decay in ECR heated discharges confined in a mirror magnetic trap. The motivation of this work is to study plasma instabilities causing perturbations of ion current during the plasma decay. Present work is devoted to time-resolved diagnostics of non-linear effects observed during the afterglow plasma decay of an 14 GHz Electron Cyclotron Resonance Ion Source (ECRIS) at JYFL operated in pulsed mode. Plasma instabilities causing perturbations of extracted ion current during the decay were observed and studied. It is shown that these perturbations are associated with precipitation of high energy electrons along the magnetic field lines and strong bursts of bremsstrahlung emission. The effect of ion source settings on the onset of the observed instabilities was investigated. Based on the experimental data and estimated plasma properties it is assumed that the instabilities are of cyclotron type. The conclusion is supported by a comparison to other type of plasma devices (SMIS 37, IAP RAS) exhibiting similar characteristics but operating in a different plasma confinement regime.

Paper

Title

Other Keywords

Page

Quantitative Determination of ¹⁴⁶Sm/¹⁴⁷Sm Ratios by Accelerator Mass Spectrometry with an ECR Ion Source and Linear Acceleration for ¹⁴⁶Sm Half-Life Measurement

ion, ECR, ion-source, target

43

N. Kinoshita
UTTAC, Tsukuba, Ibaraki, Japan
P. Collon, Y. Kashiv, D. Robertson, C.J. Schmitt, X.D. Tang
University of Notre Dame, Indiana, USA
C. Deibel
MSU, East Lansing, Michigan, USA
C. Deibel, B. DiGiovine, J.P. Greene, D. Henderson, C.L. Jiang, S.T. Marley, R.C. Pardo, E. Rehm, R.H. Scott, R.C. Vondrasek
ANL, Argonne, USA
T. Nakanishi, A. Yokoyama
Kanazawa University, Kanazawa, Japan
M. Paul
The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel

Funding: Supported by U.S. DOE, Office of Nuclear Physics, contract No. DE-AC02-06CH11357, NSF JINA Grant Nr. PHY0822648 and Science Research Prog. of Japan Society for the Promotion of Science (20740161)
The alpha-decaying ¹⁴⁶Sm nuclide is used for chronology of the Solar System and silicate mantle differentiation in planets. We performed a new determination of 146Sm half-life by measuring ¹⁴⁶Sm/¹⁴⁷Sm alpha activity and atom ratios in ¹⁴⁷Sm activated via (g,n), (n,2n) and (p,2n) reactions and obtained a value (68 Myr), smaller than that adopted so far (103 Myr), with important geochemical implications*. The experiment required determination of ¹⁴⁶Sm/¹⁴⁷Sm ratios by high-energy (6 MeV/u) accelerator mass spectrometry to discriminate ¹⁴⁶Sm from isobaric ¹⁴⁶Nd contaminant. Activated Sm targets were dissolved, chemically purified and reconverted to metallic Sm. Sputter cathodes, made by pressing the Sm metal into high-purity Al holders, were used to feed the Argonne ECR ion source. ¹⁴⁶Sm²²⁺, ¹⁴⁷Sm²²⁺ ions were alternately injected and accelerated with the ATLAS linac by proper scaling of ion source and accelerator components. A tightly-fitted quartz cylindrical liner was inserted in the ECR plasma chamber to reduce contamination from the walls. ¹⁴⁶Sm ions were eventually counted in a gas-filled magnet and ¹⁴⁷Sm ions either measured as charge current or counted after proper attenuation.
* N. Kinoshita et al., Science 334, 1614 (2012)

TUPP17

Installation and Operation of a 28 GHz Gyrotron for the RIKEN Superconducting ECR Ion Source

cathode, ion, ion-source, power-supply

71

J. Ohnishi, Y. Higurashi, T. Nakagawa
RIKEN Nishina Center, Wako, Japan

The RIKEN 28-GHz ECRIS uses a gyrotron microwave source fabricated by Mitsubishi Electric Corporation. The maximum output power is 10 kW. The gyrotron produces TE02-mode microwaves, which are converted into the TE01 mode by a mode converter. In the first test on the gyrotron performed using a dummy load, we observed the 50-300 Hz ripples of ~500 W in the output power of 1-7 kW, and it was difficult to make a stable operation in the low-power. These ripples were reduced to one-tenth by stabilizing the cathode voltage and then the gyrotron could produce microwaves from < 0.5 kW stably. The operation of the ion source with the 28 GHz gyrotron was started in 2011 and the ion source supplied U and Xe beams to the RIBF for two months. The power of the microwaves fluctuated slowly in the range of 870-1250 W, which influenced the beam current from the ion source. This fluctuation was caused by a slight change of the current of the solenoid of the gyrotron depending on the room temperature. We replaced the power supply with new one which has a current stability of 10ppm per day, and stabilized the microwave power in the range of 5% in the operation of 2 kW successfully.

WEPP03

Plasma Instability in the Afterglow of ECR Discharge Sustained in a Mirror Trap

electron, plasma, ion, ECR

125

I. Izotov, A. Mansfeld, V. Skalyga, V. Zorin
IAP/RAS, Nizhny Novgorod, Russia
T. Grahn, T. Kalvas, H. A. Koivisto, J.P.O. Komppula, P. Peura, O.A. Tarvainen, V. Toivanen
JYFL, Jyväskylä, Finland

Funding: Work was performed in frame of realization of federal targeted program "Scientific and pedagogical labor force for an innovative Russia" for 2009-2013 yy.
A number of studies have been devoted to the investigations of plasma decay in ECR heated discharges confined in a mirror magnetic trap. The motivation of this work is to study plasma instabilities causing perturbations of ion current during the plasma decay. Present work is devoted to time-resolved diagnostics of non-linear effects observed during the afterglow plasma decay of an 14 GHz Electron Cyclotron Resonance Ion Source (ECRIS) at JYFL operated in pulsed mode. Plasma instabilities causing perturbations of extracted ion current during the decay were observed and studied. It is shown that these perturbations are associated with precipitation of high energy electrons along the magnetic field lines and strong bursts of bremsstrahlung emission. The effect of ion source settings on the onset of the observed instabilities was investigated. Based on the experimental data and estimated plasma properties it is assumed that the instabilities are of cyclotron type. The conclusion is supported by a comparison to other type of plasma devices (SMIS 37, IAP RAS) exhibiting similar characteristics but operating in a different plasma confinement regime.