RESUMEN
The gasdynamic electron cyclotron resonance (ECR) ion source is a type of the device in which the ionization efficiency is achieved primarily due to a high plasma density. Because of a high particle collision rate, the confinement is determined by a gasdynamic plasma outflow from a magnetic trap. Due to high efficiency of resonant heating, electrons gain energy significantly higher than that in inductively or capacitively coupled plasmas. As a consequence of such a parameter combination, the gasdynamic ECR plasma can be a unique source of low to medium charged ions, providing a high current and an ultimate quality of an ion beam. One of the most demanded directions of its application today is a development of high-current proton injectors for modern accelerators and neutron sources of different intensities. Special plasma parameters allow for the use of diagnostic techniques, traditional for multiply charged ECR plasmas as well as for other types of discharges with a high plasma density. Among the additional techniques, one can mention the methods of numerical simulation and reconstruction of the plasma density and temperature from the parameters of the extracted ion beams. Another point is that the high plasma density makes it possible to measure it from the Stark broadening of hydrogen lines by spectroscopy of plasma emission in the visible range, which is a fairly convenient non-invasive diagnostic method. The present paper discusses the main physical aspects of the gasdynamic ECR plasma, suitable diagnostic techniques, and possibilities and future prospects for its various applications.
RESUMEN
The paper presents recent results of a "pointlike" neutron source development based on a D-D fusion in a D-loaded target caused by its bombardment with a sharply focused deuterium ion beam. These developments are undergoing at the Institute of Applied Physics of Russian Academy of Sciences in order to study a possibility to create an effective and compact device for fast-neutron radiography. The last experiments with a beam produced by a gasdynamic high-current ECR ion source and its focusing with a magnetic lens demonstrated that 60 mA of deuterium ions may be constricted to a transversal size of â¼1 mm at the focal plane. With a purpose to improve this result in terms of the beam current and its size, a combined electrostatic and magnetic focusing system is proposed and analyzed. It is shown that the combined system may enhance the total beam current and reduce its footprint down to 0.13 mm. All numerical analysis was performed using the IBSimu code.
RESUMEN
Negative hydrogen ion sources are used as injectors into accelerators and drive the neutral beam heating in ITER. Certain processes in low-temperature hydrogen plasmas are accompanied by the emission of vacuum ultraviolet (VUV) emission. Studying the VUV radiation, therefore, provides volumetric rates of plasma-chemical processes and plasma parameters. In the past, we have used gasdynamic ECR discharge for volumetric negative ion production and investigated the dependencies between the extracted H- current density and various ion source parameters. It was shown that it is possible to reach up to 80 mA/cm2 of negative ion current density with a two electrode extraction. We report experimental studies on negative hydrogen ion production in a high-density gasdynamic ECR discharge plasma consisting of two simple mirror traps together with the results of VUV emission measurements. The VUV-power was measured in three ranges-Lyα, Lyman band, and molecular continuum-varying the source control parameters near their optima for H- production. It was shown that the molecular continuum emission VUV power is the highest in the first chamber while Lyα emission prevails in the second one. Modifications for the experimental scheme for further optimization of negative hydrogen ion production are suggested.
RESUMEN
Results of experimental investigation of the ECR discharge in a single coil magnetic field as an alternative to rf and helicon discharges for wide-aperture dense plasma fluxes production are presented. A possibility of obtaining wide-aperture high density hydrogen plasma fluxes with homogeneous transverse distribution was demonstrated in such a system. The prospects of using this system for obtaining high current ion beams are discussed.
RESUMEN
A new experimental facility named GISMO (Gasdynamic Ion Source for Multipurpose Operation) was constructed at the IAP RAS to continue investigations in the field of gasdynamic ion sources. The source utilizes 28 GHz/10 kW gyrotron radiation for heating magnetically confined plasma. Magnetic field configuration provided by a fully permanent magnet system is much like a simple mirror trap. The GISMO source is aimed at the production of bright ion beams with hundreds of milliamperes current. The facility has been tested for continuous-wave (CW) operation with 2 kW of heating power to check durability of a microwave injection system and the plasma chamber. A 2-electrode extraction system with an integrated Einzel lens was designed for a formation of CW high current beam with up to 100 kV accelerating voltage. The first results on ion beam production at GISMO are presented together with the general progress status of the facility.
RESUMEN
We report the first experimental evidence of a controlled transition from the generation of periodic bursts of electromagnetic radiation into the continuous-wave regime of a cyclotron maser formed in magnetically confined nonequilibrium plasma. The kinetic cyclotron instability of the extraordinary wave of weakly inhomogeneous magnetized plasma is driven by the anisotropic electron population resulting from electron cyclotron plasma heating in a MHD-stable minimum-B open magnetic trap.
RESUMEN
Plasma of electron cyclotron resonance (ECR) discharge sustained by millimeter wave radiation is widely used for production of ion beams of different kind. The main trend in ECR ion sources development nowadays is an increase of frequency and power of microwave heating. The most advanced systems use gyrotrons in 24-60 GHz frequency range. In previous studies at IAP RAS it was demonstrated that ECR source SMIS 37 (Simple Mirror Ion Source) with 37.5 GHz heating operating in quasigasdynamic regime of plasma confinement is able to produce proton and deuteron beams with ion current density about 700 mA/cm2. As the next step of these investigations plasma properties of the discharge sustained by 75 GHz radiation have been studied. Plasma density and electron temperature were determined using spectroscopic and Langmuir probe techniques. It was demonstrated that plasma density could reach values close to 1014 cm-3 and that is of great interest for further development of high current ion sources for various applications.
RESUMEN
Influence of shear flows of the dense plasma created under conditions of the electron cyclotron resonance (ECR) gas breakdown on the plasma confinement in the axisymmetric mirror trap ("vortex" confinement) was studied experimentally and theoretically. A limiter with bias potential was set inside the mirror trap for plasma rotation. The limiter construction and the optimal value of the potential were chosen according to the results of the preliminary theoretical analysis. This method of "vortex" confinement realization in an axisymmetric mirror trap for non-equilibrium heavy-ion plasmas seems to be promising for creation of ECR multicharged ion sources with high magnetic fields, more than 1 T.
RESUMEN
Numerical analysis of (6)He atoms utilizing efficiency in the ion source with powerful gyrotron heating is performed in present work using zero-dimensional balanced model of ECR discharge in a magnetic trap. Two ways of creation of ion source with high gas utilization efficiency (up to 60%-90%) are suggested.
RESUMEN
A careful study of pulsed mode operation of the PHOENIX electron cyclotron resonance (ECR) ion source has clearly demonstrated the reality of an unexpected transient current peak, occurring at the very beginning of the plasma breakdown. This regime was named the preglow, as an explicit reference to the afterglow occurring at the microwave pulse end. After the transient preglow peak, the plasma regime relaxes to the classical steady state one. Argon preglow experiments performed at LPSC are presented. A theoretical model of ECR gas breakdown in a magnetic trap, developed at IAP, showing satisfactory agreement with the experimental results is suggested.