Vladimir ZORIN Institute of Applied Physics Nizhny Novgorod, Russia Additional Partner in EUROnu project ECR task: continuation of work with a 60 GHz ECR ion source for bunching studies of 6 He and 18 Ne started within EURISOL DS with the objective of reaching the high efficiencies needed for the beta-beam.

high efficiencies – how to reach? high gas efficiencies Proper pulse duration Proper ion extraction

Today’s my report about Proper pulse duration

Requirement for ion beam pulses Duration ~ 100 µs 100 µs 28 GHz Grenoble T. Lamy at al

Two approaches for creation of short pulse multicharged ion beams Short pulse ECR ion source Steady state generation Non-steady state (preglow & afterglow effects)

Steady state approach on generation of short pulses Plasma confinement time << pulse duration ~ 100µs Plasma confinement time ~ 10 – 20µs Quasi-gasdynamic plasma confinement

25 s Total extracted ion current End of MW pulse Rising time of total extracted ion current is ~15 s !!! Steady state approach on generation of short pulses, 37 GHz December 2005 Gyrotron 37.5 GHz, 100 kW Gasdynamic plasma confinement Cusp trap with 25 cm effective length Working gas is He

Ion spectrum during the steady-state Air contamination is from input gas (we used a pillow for He) Low plasma confinement time

Steady state approach, 75 GHz Rising time ≈ 15 µs Average charge ≈ 1,5 Simulation Experiment MW power 250 kW Magnetic field 3,5 T В.А. Скалыга, В.Г. Зорин, И.В. Изотов, А.В. Водопьянов, С.В. Голубев, Д.А. Мансфельд, С.В. Разин, А.В. Сидоров. Короткоимпульсный ЭЦР источник многозарядных ионов. ЖТФ A.V. Vodopyanov, S.V. Golubev, I.V. Izotov, V.I. Khizhnyak. D.A. Mansfeld, V.A. Skalyga and V.G. Zorin. ECR Plasma With 75 GHz Pumping. High Energy Physics and Nuclear Physics. 2007, 31(S1): 152—155. End of MW

Non-steady state approach 28 GHz Preglow Afterglow Pulse duration can not be<< Duration of Preglow ~ - confinement time Ion beam waveform Duration of Afterglow ~

Non-steady state approach confinement time Axi symmetrical mirror magnetic trap

Generation of short pulses of MCI in ECR ion source Experiments, gyrotron 37 GHz, March 2010 Ion current of Ar 4+ T свч =70 µsT свч =60 µsT свч =50 µsT свч =40 µs Just noise Duration of ion current vs microwave duration

MW pulse Ion current of N 3+ Microwave duration = 50 µs Duration of ion current = 20 µs Ion current of N 3+ = 2 мА 20 µs So,

Charge state distribution in short pulses C 2+ Argon Ar 3+ Ar 4+ Ar 5+ Ar 2+ C 2+ N 2+ C+C+ O+O+ Nitrogen H+H+ N+N+ N 2+ N 3+ N 4+ O 2+ O 3+ O+O+ C 2+ C 3+ C+C+

Steady state vs non-steady state Charge of ions Magnet current, eA Analyzer signal, a.u. Magnet current, A Nitrogen H+H+ N+N+ N 2+ N 3+ N 4+ O 2+ O 3+ O+O+ C 2+ C 3+ C+C+ Steady state Non-steady state

Modeling of short pulses Simple mirror trap, L=37 cm Mirror Ratio = 4 MW=10 kW/cm 2 Extraction voltage = 25 kV MW duration ~ 70 µs Experiment Modeling

Further but nearest experiments: He, Ne charge distribution, optimization control of pulse duration in experiments ion extraction emittance measurements MHD influence, when is it negligible?