Search results for "MAS"
showing 10 items of 18047 documents
Mass calibration of the energy axis in ToF- E elastic recoil detection analysis
2016
We report on procedures that we have developed to mass-calibrate the energy axis of ToF-E histograms in elastic recoil detection analysis. The obtained calibration parameters allow one to transform the ToF-E histogram into a calibrated ToF-M histogram.
The effect of plasma electrode collar structure on the performance of the JYFL 14GHz electron cyclotron resonance ion source
2013
Abstract The influence of a so-called collar structure on the performance of the JYFL 14 GHz electron cyclotron resonance ion source (ECRIS) has been studied experimentally at the Department of Physics, University of Jyvaskyla (JYFL). The collar is a cylindrical structure extruding inwards from the plasma electrode. The collar length was varied between 5 and 60 mm. For some ion species a moderate performance improvement was achieved in terms of extracted beam current and transverse emittance up to 30 mm collar length. Longer collars resulted in a substantial performance decrease. Different collar materials, i.e. nonmagnetic stainless steel, aluminum and Al 2 O 3 , and a wide range of ion sp…
System for control of polarization state of light and generation of light with continuously rotating linear polarization
2019
We present a technique for generating light in an arbitrary polarization state. The technique is based on interference of two orthogonally polarized light beams, whose amplitudes and phases are controlled with a Mach-Zehnder inteferometer with acousto-optic modulators (AOMs) placed in each arm. We demonstrate that via control over amplitudes, phases, and frequencies of acoustic waves driving the AOMs, any polarization state can be synthesized. In particular, we demonstrate generation of linearly polarized light, whose polarization plane continuously rotates at a rate from 1 kHz to 1 MHz. Such light finds applications in science (e.g., investigations of Bloch-Siegert effect) and technology (…
Time resolved measurements of hydrogen ion energy distributions in a pulsed 2.45 GHz microwave plasma
2017
A plasma diagnostic study of the Ion Energy Distribution Functions (IEDFs) of H+, H+2H2+, and H+3H3+ ions in a 2.45 GHz hydrogen plasma reactor called TIPS is presented. The measurements are conducted by using a Plasma Ion Mass Spectrometer with an energy sector and a quadrupole detector from HIDEN Analytical Limited in order to select an ion species and to measure its energy distribution. The reactor is operated in the pulsed mode at 100 Hz with a duty cycle of 10% (1 ms pulse width). The IEDFs of H+, H+2H2+, and H+3H3+ are obtained each 5 μs with 1 μs time resolution throughout the entire pulse. The temporal evolution of the plasma potential and ion temperature of H+ is derived from the d…
Measurements of the energy distribution of electrons lost from the minimum B-field -- the effect of instabilities and two-frequency heating
2020
Further progress in the development of ECR ion sources (ECRIS) requires deeper understanding of the underlying physics. One of the topics that remains obscure, though being crucial for the performance of the ECRIS, is the electron energy distribution (EED). A well-developed technique of measuring the EED of electrons escaping axially from the magnetically confined plasma of an ECRIS was used for the study of EED in unstable mode of plasma confinement, i.e. in the presence of kinetic instabilities. The experimental data were recorded for pulsed and CW discharges with a room-temperature 14 GHz ECRIS at the JYFL accelerator laboratory. The measurements were focused on observing differences bet…
Charge breeding at GANIL: Improvements, results, and comparison with the other facilities
2019
International audience; The 1+/n+ method, based on an ECRIS charge breeder (CB) originally developed at the LPSC laboratory, is now implemented at GANIL for the production of Radioactive Ion Beams (RIBs). Prior to its installation in the middle of the low energy beam line of the SPIRAL1 facility, the 1+/n+ system CB has been modified based on the experiments performed on the CARIBU Facility at Argone National Laboratory. Later, it has been tested at the 1+/n+ LPSC test bench to validate its operation performances. Charge breeding efficiencies as well as charge breeding times have been measured for noble gases and alkali elements. The commissioning phase started at GANIL in the second half-y…
Self-consistent non-stationary theory of the gyrotron
2016
For a long time, the gyrotron theory was developed assuming that the transit time of electrons through the interaction space is much shorter than the cavity fill time. Correspondingly, it was assumed that during this transit time, the amplitude of microwave oscillations remains constant. A recent interest to such additional effects as the after-cavity interaction between electrons and the outgoing wave in the output waveguide had stimulated some studies of the beam-wave interaction processes over much longer distances than a regular part of the waveguide which serves as a cavity in gyrotrons. Correspondingly, it turned out that the gyrotron theory free from the assumption about constant amp…
Effects of magnetic configuration on hot electrons in a minimum-B ECR plasma
2020
International audience; To investigate the hot electron population and the appearance of kinetic instabilities in highly charged electron cyclotron resonance ion source (ECRIS), the axially emitted bremsstrahlung spectra and microwave bursts emitted from ECRIS plasma were synchronously measured on SECRAL-II (Superconducting ECR ion source with Advanced design in Lanzhou No. II) ion source with various magnetic field configurations. The experimental results show that when the ratio of the minimum field to the resonance field (i.e. Bmin/Becr ) is less than ~0.8, the bremsstrahlung spectral temperature Ts increases linearly with the Bmin/Becr –ratio when the injection, extraction and radial mi…
Hydrogen plasma induced photoelectron emission from low work function cesium covered metal surfaces
2017
Experimental results of hydrogen plasma induced photoelectron emission from cesium covered metal surfaces under ion source relevant conditions are reported. The transient photoelectron current during the Cs deposition process is measured from Mo, Al, Cu, Ta, Y, Ni, and stainless steel (SAE 304) surfaces. The photoelectron emission is 2–3.5 times higher at optimal Cs layer thickness in comparison to the clean substrate material. Emission from the thick layer of Cs is found to be 60%–80% lower than the emission from clean substrates. peerReviewed
Cyclotron instability in the afterglow mode of minimum-B ECRIS.
2016
It was shown recently that cyclotron instability in non-equilibrium plasma of a minimum-B electron cyclotron resonance ion source (ECRIS) causes perturbation of the extracted ion current and generation of strong bursts of bremsstrahlung emission, which limit the performance of the ion source. The present work is devoted to the dynamic regimes of plasma instability in ECRIS operated in pulsed mode. Instability develops in decaying plasma shortly after heating microwaves are switched off and manifests itself in the form of powerful pulses of electromagnetic emission associated with precipitation of high energy electrons. Time-resolved measurements of microwave emission bursts are presented. I…