Andrey Sanin - Academia.edu (original) (raw)

Papers by Andrey Sanin

AIP Conference Proceedings, 2009

ABSTRACT A cw surface-plasma type negative ion source has been developed. H- beam with current 15... more ABSTRACT A cw surface-plasma type negative ion source has been developed. H- beam with current 15 mA and energy of 32 keV is regularly produced in the runs with duration >102 hours. Unattended operation of the source under computer control is realized. The source has a simplified maintenance and an easy access to consumable parts.

Production of the electron beam with a high current density in a foilless plasma-filled diode, im... more Production of the electron beam with a high current density in a foilless plasma-filled diode, immersed in a strong axial magnetic field, is studied. The plasma parameters in the diode are investigated with the CO2 laser interferometer (λ = 10.6 µm ) in a wide range of temporal scales - from hundreds of microseconds for the preliminary plasma, filling the

Instruments and Experimental Techniques, 2004

An infrared interferometer built according to the Mach–Zehnder design without a frame is describe... more An infrared interferometer built according to the Mach–Zehnder design without a frame is described. The interferometer was used in measurements of the plasma-density dynamics inside a plasma-filled diode under conditions of intense vibrations. Such measurements can be performed under conditions of a quite short plasma lifetime, compared to the characteristic vibration period of the interferometer elements.

Production of the electron beam with a high current density in a foilless plasma-filled diode, im... more Production of the electron beam with a high current density in a foilless plasma-filled diode, immersed in a strong axial magnetic field, is studied. The plasma parameters in the diode are investigated with the CO2 laser interferometer (λ = 10.6 µm ) in a wide range of temporal scales - from hundreds of microseconds for the preliminary plasma, filling the diode gap, down to tens of nanoseconds for the explosive cathode plasma during the time of beam generation. The determined dependences of the beam parameters on the density of preliminary plasma made it possible to optimize the design of foilless diode for the purpose of obtaining an electron beam with diameter of about 0.5 cm and current density more than 50 kA/cm2.

Plasma Physics Reports

The possibilities to use a CO{sub 2} laser for the detection of plasma density fluctuations in th... more The possibilities to use a CO{sub 2} laser for the detection of plasma density fluctuations in the gigahertz frequency range are discussed. The following experiments are considered: Splashing ion distribution function measurements in the hydrogen prototype of a neutron source on the base of a gasodynamical trap; the study of runaway electron dynamics in big tokamaks; ion distribution function diagnostics for the ITER-type tokamak. Our estimations of the above methods` feasibility are partially based on the experience of operating the previously developed laser scattering system. This system was used in experiments to study Langmuir turbulence excited by a relativistic electron beam. 7 refs., 4 figs.

A CO2 laser imaging interferometer is developing on Large Helical Device (LHD) (1). It is designe... more A CO2 laser imaging interferometer is developing on Large Helical Device (LHD) (1). It is designed for high spatial resolution measurements of both density profile and fluctuations especially at la rge density regimes. Three vertical slab probe beams cover almost entire plasma cross-section. As the first step one probe beam interferometer was installed and examined during the fifth LHD experim ental campaign (Sept., 2001-Febr., 2002). Results obtained with heterodyne interferometer (HI) show fine resolution in the plasma boundary and no fringe jump during pellet injection (2). The phase contrast interferometer mode (PCI) detected plasma density fluctuations (3). The arrangement of the imaging part of the interferometer is chosen flexible to test several modifications of imaging interferometry in experim ents. Two of the modifications use diffraction effects and are intended to obtain spatial resolution along the viewing line and to increase the sensitivity for detection of small-sca...

Two modifications of imaging interferometry: heterodyne (HI) and phase contrast interferometers (... more Two modifications of imaging interferometry: heterodyne (HI) and phase contrast interferometers (PCI) are designed for observation of plasma density profiles and density fluctuations respectively. Besides, spatial distributions of plasma velocities, velocities fluctuations and related electrical fields can be obtained from the analysis of HI and PCI data. New sensitive phase counters, developed at Budker Institute of Nuclear Physics, enable HI to include some capabilities of the PCI. In addition to well recognized transversal spatial resolution of imaging technique, progress in deconvolution of line-of-sight-integrated data was recently made. Computer simulation, bench-test experiments and recent experimental results from the Large Helical Device illustrate the potentials of the imaging interferometry for investigation of plasma. Application of the imaging interferometry with spatial resolution along the viewing line to mirror machines is finally considered.

Study of current fluctuations for cw Penning SPS with hollow cathode drive was done. The noisepro... more Study of current fluctuations for cw Penning SPS with hollow cathode drive was done. The noiseproof measurements of negative ion beam current, current in extracted electrode circuit, discharge current and voltage were carried out by the low-inductive probes in wide frequency range. Spectrum and intensity of fluctuations at various operation modes, parameters and electrode geometry were recorded for two versions

Scattering radiation from a COâ laser is used to carry out direct observations of Langmuir oscill... more Scattering radiation from a COâ laser is used to carry out direct observations of Langmuir oscillations associated with the interaction between a high-power relativistic electron beam and a plasma. Experimental data on the frequency spectrum of the turbulence and the first results on studies of the spatial spectra of the oscillations are presented. 4 refs., 2 figs.

Review of Scientific Instruments, 2014

The ion source with the Penning geometry of electrodes producing continuous-wave beam of H(-) ion... more The ion source with the Penning geometry of electrodes producing continuous-wave beam of H(-) ions with current up to 25 mA was developed. Several improvements were introduced to increase source intensity, reliability, and lifetime. The collar around the emission aperture increases the electrons filtering. The apertures' diameters of the ion-optical system electrodes were increased to generate the beam with higher intensity. An optimization of electrodes' temperature was performed.

Review of Scientific Instruments, 2006

ABSTRACT The two-dimensional (2D) phase contrast imaging system on LHD can measure the k spectrum... more ABSTRACT The two-dimensional (2D) phase contrast imaging system on LHD can measure the k spectrum of line-integrated density fluctuations (k ∼ 0.2–3 mm−1 and k⊥ρi ∼ 0.1–1.5) with modest spatial resolution (Δρ ∼ 0.1) along a line of sight passing close to the magnetic axis, sensitive to radial fluctuations in the core and poloidal fluctuations in the edge. The spatial resolution is attained using a 6×8 2D detector array taking advantage of the strong magnetic shear in LHD. The system can be configured with different magnification factors to investigate different ranges of k (in “overview” mode from 0.2 to 0.6 mm−1, characteristic of ITG/TEM scale turbulence; and “zoom” mode from 1 to 3 mm−1, which may access to the lower limit of the ETG range). Zoom mode additionally employs cylindrical optics to stretch the image by a factor of 4 in order to provide better spatial resolution for high k fluctuations within a narrow spatial region. The highest detected value of k in zoom mode, for which the signal-to-noise ratio is better than 1, is 2.5 mm−1 (at around 1.5 MHz).

Review of Scientific Instruments, 2006

Status of direct current hydrogen negative-ion source development for tandem accelerator is descr... more Status of direct current hydrogen negative-ion source development for tandem accelerator is described. The electrodes enforcing its water cooling and introducing of the electrons' interception permitted to increase the source discharge power and to obtain regularly the H--ion beam with energy >25 kV and current up to 15 mA.

AIP Conference Proceedings, 2009

ABSTRACT A cw surface-plasma type negative ion source has been developed. H- beam with current 15... more ABSTRACT A cw surface-plasma type negative ion source has been developed. H- beam with current 15 mA and energy of 32 keV is regularly produced in the runs with duration >102 hours. Unattended operation of the source under computer control is realized. The source has a simplified maintenance and an easy access to consumable parts.

Production of the electron beam with a high current density in a foilless plasma-filled diode, im... more Production of the electron beam with a high current density in a foilless plasma-filled diode, immersed in a strong axial magnetic field, is studied. The plasma parameters in the diode are investigated with the CO2 laser interferometer (λ = 10.6 µm ) in a wide range of temporal scales - from hundreds of microseconds for the preliminary plasma, filling the

Instruments and Experimental Techniques, 2004

An infrared interferometer built according to the Mach–Zehnder design without a frame is describe... more An infrared interferometer built according to the Mach–Zehnder design without a frame is described. The interferometer was used in measurements of the plasma-density dynamics inside a plasma-filled diode under conditions of intense vibrations. Such measurements can be performed under conditions of a quite short plasma lifetime, compared to the characteristic vibration period of the interferometer elements.

Production of the electron beam with a high current density in a foilless plasma-filled diode, im... more Production of the electron beam with a high current density in a foilless plasma-filled diode, immersed in a strong axial magnetic field, is studied. The plasma parameters in the diode are investigated with the CO2 laser interferometer (λ = 10.6 µm ) in a wide range of temporal scales - from hundreds of microseconds for the preliminary plasma, filling the diode gap, down to tens of nanoseconds for the explosive cathode plasma during the time of beam generation. The determined dependences of the beam parameters on the density of preliminary plasma made it possible to optimize the design of foilless diode for the purpose of obtaining an electron beam with diameter of about 0.5 cm and current density more than 50 kA/cm2.

Plasma Physics Reports

The possibilities to use a CO{sub 2} laser for the detection of plasma density fluctuations in th... more The possibilities to use a CO{sub 2} laser for the detection of plasma density fluctuations in the gigahertz frequency range are discussed. The following experiments are considered: Splashing ion distribution function measurements in the hydrogen prototype of a neutron source on the base of a gasodynamical trap; the study of runaway electron dynamics in big tokamaks; ion distribution function diagnostics for the ITER-type tokamak. Our estimations of the above methods` feasibility are partially based on the experience of operating the previously developed laser scattering system. This system was used in experiments to study Langmuir turbulence excited by a relativistic electron beam. 7 refs., 4 figs.

A CO2 laser imaging interferometer is developing on Large Helical Device (LHD) (1). It is designe... more A CO2 laser imaging interferometer is developing on Large Helical Device (LHD) (1). It is designed for high spatial resolution measurements of both density profile and fluctuations especially at la rge density regimes. Three vertical slab probe beams cover almost entire plasma cross-section. As the first step one probe beam interferometer was installed and examined during the fifth LHD experim ental campaign (Sept., 2001-Febr., 2002). Results obtained with heterodyne interferometer (HI) show fine resolution in the plasma boundary and no fringe jump during pellet injection (2). The phase contrast interferometer mode (PCI) detected plasma density fluctuations (3). The arrangement of the imaging part of the interferometer is chosen flexible to test several modifications of imaging interferometry in experim ents. Two of the modifications use diffraction effects and are intended to obtain spatial resolution along the viewing line and to increase the sensitivity for detection of small-sca...

Two modifications of imaging interferometry: heterodyne (HI) and phase contrast interferometers (... more Two modifications of imaging interferometry: heterodyne (HI) and phase contrast interferometers (PCI) are designed for observation of plasma density profiles and density fluctuations respectively. Besides, spatial distributions of plasma velocities, velocities fluctuations and related electrical fields can be obtained from the analysis of HI and PCI data. New sensitive phase counters, developed at Budker Institute of Nuclear Physics, enable HI to include some capabilities of the PCI. In addition to well recognized transversal spatial resolution of imaging technique, progress in deconvolution of line-of-sight-integrated data was recently made. Computer simulation, bench-test experiments and recent experimental results from the Large Helical Device illustrate the potentials of the imaging interferometry for investigation of plasma. Application of the imaging interferometry with spatial resolution along the viewing line to mirror machines is finally considered.

Study of current fluctuations for cw Penning SPS with hollow cathode drive was done. The noisepro... more Study of current fluctuations for cw Penning SPS with hollow cathode drive was done. The noiseproof measurements of negative ion beam current, current in extracted electrode circuit, discharge current and voltage were carried out by the low-inductive probes in wide frequency range. Spectrum and intensity of fluctuations at various operation modes, parameters and electrode geometry were recorded for two versions

Scattering radiation from a COâ laser is used to carry out direct observations of Langmuir oscill... more Scattering radiation from a COâ laser is used to carry out direct observations of Langmuir oscillations associated with the interaction between a high-power relativistic electron beam and a plasma. Experimental data on the frequency spectrum of the turbulence and the first results on studies of the spatial spectra of the oscillations are presented. 4 refs., 2 figs.

Review of Scientific Instruments, 2014

The ion source with the Penning geometry of electrodes producing continuous-wave beam of H(-) ion... more The ion source with the Penning geometry of electrodes producing continuous-wave beam of H(-) ions with current up to 25 mA was developed. Several improvements were introduced to increase source intensity, reliability, and lifetime. The collar around the emission aperture increases the electrons filtering. The apertures' diameters of the ion-optical system electrodes were increased to generate the beam with higher intensity. An optimization of electrodes' temperature was performed.

Review of Scientific Instruments, 2006

ABSTRACT The two-dimensional (2D) phase contrast imaging system on LHD can measure the k spectrum... more ABSTRACT The two-dimensional (2D) phase contrast imaging system on LHD can measure the k spectrum of line-integrated density fluctuations (k ∼ 0.2–3 mm−1 and k⊥ρi ∼ 0.1–1.5) with modest spatial resolution (Δρ ∼ 0.1) along a line of sight passing close to the magnetic axis, sensitive to radial fluctuations in the core and poloidal fluctuations in the edge. The spatial resolution is attained using a 6×8 2D detector array taking advantage of the strong magnetic shear in LHD. The system can be configured with different magnification factors to investigate different ranges of k (in “overview” mode from 0.2 to 0.6 mm−1, characteristic of ITG/TEM scale turbulence; and “zoom” mode from 1 to 3 mm−1, which may access to the lower limit of the ETG range). Zoom mode additionally employs cylindrical optics to stretch the image by a factor of 4 in order to provide better spatial resolution for high k fluctuations within a narrow spatial region. The highest detected value of k in zoom mode, for which the signal-to-noise ratio is better than 1, is 2.5 mm−1 (at around 1.5 MHz).

Review of Scientific Instruments, 2006

Status of direct current hydrogen negative-ion source development for tandem accelerator is descr... more Status of direct current hydrogen negative-ion source development for tandem accelerator is described. The electrodes enforcing its water cooling and introducing of the electrons' interception permitted to increase the source discharge power and to obtain regularly the H--ion beam with energy >25 kV and current up to 15 mA.