IAP/RAS, Nizhny Novgorod, Russia
This work is a continuation of the experiments described in [1, 2] and aimed at the investigation of the new conceptions of MHD stabilization of plasma in open axisymmetric traps, specifically, it is aimed at the investigation of the shear flow influence on the transport control in open mirror traps. As in previous experiments, shear flow was created by limiter-electrode with bias potential according to the vacuum chamber. Plasma density structure in radial and azimuthal directions was studied. Mode structure of the perturbations was investigated. Substantial sharp shift of the plasma density maximum to the system axis with bias potential growth was demonstrated. It was shown, that the value of the bias potential that corresponds to the plasma density profile shift grows with the magnetic field growth that can be interpreted as the electron temperature growth. Some theoretical estimations of the influence of the transversal losses decrease on plasma parameters were made.
[1] A.Sidorov, P.Bagryansky, A.Beklemishev et al. Trans. Fusion Sci. and Technology, 59, 112, (2011).
[2] I.Izotov, S.Razin, A.Sidorov et al. Rev. Sci. Instrum., 83, 02A318 (2012).
IAP/RAS, Nizhny Novgorod, Russia
JYFL, Jyväskylä, Finland
Operation of modern high power accelerators often requires production of intense beams of hydrogen ions. Newer facilities aiming at outperforming the previous generation accelerators are usually designed for higher beam currents. Meeting the demand for hydrogen ion beams with higher intensity and low transverse emittance is, therefore, becoming increasingly difficult problem. Present work is devoted to experimental investigation of proton beams production from dense plasma (Ne>1013 cm-3) of ECR discharge sustained by 37.5 GHz, 100 kW gyrotron radiation at SMIS 37 facility at IAP RAS. Different extraction system configurations were used. It was demonstrated that ultra bright proton beam with 4.5 mA current and 0.1 π·mm·mrad normalized emittance (brightness=45 A/(π·mm·mrad)2) can be formed with 1-hole (1 mm in diameter) extraction. For production of high current beams a 13-hole extractor was used. 200 mA and 1.1 π·mm·mrad normalized emittance proton beam was obtained. A possibility of further beam parameters enhancement by developing of extraction system and its power supply is discussed. It was shown that in generated proton beams H2+ component was less than 6%.
LPSC, Grenoble Cedex, France
GHMFL, Grenoble, France
IAP/RAS, Nizhny Novgorod, Russia
LPSC and LNCMI (Laboratoire National des Champs Magnétiques Intenses) of Grenoble have developed the first and unique magnetic confinement structure in the world that allows a closed 60 GHz ECR zone, using high field magnet technologies. The magnetic structure has been validated for 28 GHz resonance and a closed 1 T iso-B surface was measured. Calculated and measured field maps were carefully compared in order to determine an operation range for 28 GHz plasma tests. A whole test bench, including high pressure water for helix cooling, intense currents (up to 15 kA) for helix powering and a beam line with mass separation is under construction at LNCMI. This contribution presents the status of the experiment, hopefully including the results of the first beam tests scheduled in September. The 350 kW - 60 GHz gyrotron has been built at IAP, the status of its operation will be shown.
IAP/RAS, Nizhny Novgorod, Russia
JYFL, Jyväskylä, Finland
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.