Ion source modification is proposed for efficient production of ion beam and extending of operati... more Ion source modification is proposed for efficient production of ion beam and extending of operating Lifetime. Ionization efficiency of the Bernas type ion source has been improved by using a small anode-thin rod, oriented along the magnetic field. The transverse electric field of small anode transport plasma by drift in crossed field to the emission slit. Optimization of the cathode material recycling is used to increase the operating lifetime. Optimization of the wall potential is used for suppression of flakes formation. A three-electrode extraction system was optimized for low energy beam production and efficient space charge neutralization. An ion beam with emission current density up to 60 mA/cm2 has been extracted from discharge in BF3 gas.
A RF discharge plasma generator with additional electrodes for independent control of plasma pote... more A RF discharge plasma generator with additional electrodes for independent control of plasma potential distribution is proposed. With positive biasing of this ring electrode relative end flanges and longitudinal magnetic field a confinement of fast electrons in the discharge will be improved for reliable triggering of pulsed RF discharge at low gas density and rate of ion generation will be enhanced. In the proposed discharge combination, the electron energy is enhanced by RF field and the fast electron confinement is improved by enhanced positive plasma potential which improves the efficiency of plasma generation significantly. This combination creates a synergetic effect with a significantly improving the plasma generation performance at low gas density. The discharge parameters can be optimized for enhance plasma generation with acceptable electrode sputtering.
A prototype RF H(-) surface plasma source (SPS) with saddle (SA) RF antenna is developed which wi... more A prototype RF H(-) surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA∕kW. Control experiments with H(-) beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing.
The emission of streams of accelerated atoms from a glow discharge in hydrogen with a cesium mixt... more The emission of streams of accelerated atoms from a glow discharge in hydrogen with a cesium mixture has been studied. The streams occur because the cesium intensifies the surface-plasma mechanism for the formation of negative ions. The operation of a surface-plasma source of accelerated atoms with a ''semiplanotron'' electrode configuration has been studied. A pulsed barretter with a sensitivity of 1 mA/J was used to measure the flux density. The atoms underwent charge exchange into neagative ions in a cesium target for measurement of the energy distribution. The source generates accelerated atoms with energies in the range 200--600 eV, determined by the discharge voltage. The efficiency of the source increases greatly as the cesium supply rate is increased. Beams of accelerated hydrogen atoms with an equivalent current of 2.7 A and an emission density up to 3 A/cm/sup 2/ have been obtained at a discharge voltage of 200 V.
Springer Series on Atomic, Optical, and Plasma Physics, 2019
The development of the surface plasma method of negative ion beam production; classification of s... more The development of the surface plasma method of negative ion beam production; classification of surface plasma sources; recent developments in surface plasma sources.
The secondary-emission characteristics of the electrodes in surface-plasma sources are studied as... more The secondary-emission characteristics of the electrodes in surface-plasma sources are studied as part of a study of the processes leading to the formation of H/sup -/ ions. Measurements of the emission of fast positive ions through narrow slits in the cathodes of the Penning cell show that, when cesium is admitted into high-current glow discharges with electron oscillation in a magnetic field, the generalized yield of secondary electron emission from the cathode increases by a factor of tens, from 0.1--0.2 to 5--6. Estimates show that the secondary-emission yield of H/sup -/ ions correspondingly increases from 0.01 to 0.6--0.8.
Increased interest in the development of negative ions sources is related to the emergence of imp... more Increased interest in the development of negative ions sources is related to the emergence of important applications of negative-ion beams. These are, first of all, tandem accelerators, high-energy implantation and accelerator-based mass spectrometry, supercollimated beams, charge-exchange injection into cyclic accelerators and storage rings, charge-exchange extraction of beams from cyclotrons, injectors of high-energy neutrals in plasma systems, and charge-exchange beam separation. The development of sources of negative ions and their use in academic research and industry are reviewed. Physical bases and designs of surface-plasma sources of negative ions, as well as the history of their development, are presented.
This paper examines topics related to the production of H- beams of maximum brightness in surface... more This paper examines topics related to the production of H- beams of maximum brightness in surface-plasma sources. It is shown that a maximum brightness of ˜2×108 A/cm2 rad2 can be obtained in Penning geometry sources in which efficient generation of negative ions with a reduced energy of ion thermal motion in the plasma of <=0.5 eV is possible under optimized
A surface-plasma source of H- ions with a semiplanotron geometry of the discharge chamber was inv... more A surface-plasma source of H- ions with a semiplanotron geometry of the discharge chamber was investigated. The discharge was localized around the emission slit of 0.5×10 mm2, and a cylindrical cathode surface serves for geometrical focussing of H- ions. The H- beam current was up to 0.15A, normalized brightness to 108 A/cm2rad2, pulse length 200 mus and no cooling was
Ion source modification is proposed for efficient production of ion beam and extending of operati... more Ion source modification is proposed for efficient production of ion beam and extending of operating Lifetime. Ionization efficiency of the Bernas type ion source has been improved by using a small anode-thin rod, oriented along the magnetic field. The transverse electric field of small anode transport plasma by drift in crossed field to the emission slit. Optimization of the cathode material recycling is used to increase the operating lifetime. Optimization of the wall potential is used for suppression of flakes formation. A three-electrode extraction system was optimized for low energy beam production and efficient space charge neutralization. An ion beam with emission current density up to 60 mA/cm2 has been extracted from discharge in BF3 gas.
A RF discharge plasma generator with additional electrodes for independent control of plasma pote... more A RF discharge plasma generator with additional electrodes for independent control of plasma potential distribution is proposed. With positive biasing of this ring electrode relative end flanges and longitudinal magnetic field a confinement of fast electrons in the discharge will be improved for reliable triggering of pulsed RF discharge at low gas density and rate of ion generation will be enhanced. In the proposed discharge combination, the electron energy is enhanced by RF field and the fast electron confinement is improved by enhanced positive plasma potential which improves the efficiency of plasma generation significantly. This combination creates a synergetic effect with a significantly improving the plasma generation performance at low gas density. The discharge parameters can be optimized for enhance plasma generation with acceptable electrode sputtering.
A prototype RF H(-) surface plasma source (SPS) with saddle (SA) RF antenna is developed which wi... more A prototype RF H(-) surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA∕kW. Control experiments with H(-) beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing.
The emission of streams of accelerated atoms from a glow discharge in hydrogen with a cesium mixt... more The emission of streams of accelerated atoms from a glow discharge in hydrogen with a cesium mixture has been studied. The streams occur because the cesium intensifies the surface-plasma mechanism for the formation of negative ions. The operation of a surface-plasma source of accelerated atoms with a ''semiplanotron'' electrode configuration has been studied. A pulsed barretter with a sensitivity of 1 mA/J was used to measure the flux density. The atoms underwent charge exchange into neagative ions in a cesium target for measurement of the energy distribution. The source generates accelerated atoms with energies in the range 200--600 eV, determined by the discharge voltage. The efficiency of the source increases greatly as the cesium supply rate is increased. Beams of accelerated hydrogen atoms with an equivalent current of 2.7 A and an emission density up to 3 A/cm/sup 2/ have been obtained at a discharge voltage of 200 V.
Springer Series on Atomic, Optical, and Plasma Physics, 2019
The development of the surface plasma method of negative ion beam production; classification of s... more The development of the surface plasma method of negative ion beam production; classification of surface plasma sources; recent developments in surface plasma sources.
The secondary-emission characteristics of the electrodes in surface-plasma sources are studied as... more The secondary-emission characteristics of the electrodes in surface-plasma sources are studied as part of a study of the processes leading to the formation of H/sup -/ ions. Measurements of the emission of fast positive ions through narrow slits in the cathodes of the Penning cell show that, when cesium is admitted into high-current glow discharges with electron oscillation in a magnetic field, the generalized yield of secondary electron emission from the cathode increases by a factor of tens, from 0.1--0.2 to 5--6. Estimates show that the secondary-emission yield of H/sup -/ ions correspondingly increases from 0.01 to 0.6--0.8.
Increased interest in the development of negative ions sources is related to the emergence of imp... more Increased interest in the development of negative ions sources is related to the emergence of important applications of negative-ion beams. These are, first of all, tandem accelerators, high-energy implantation and accelerator-based mass spectrometry, supercollimated beams, charge-exchange injection into cyclic accelerators and storage rings, charge-exchange extraction of beams from cyclotrons, injectors of high-energy neutrals in plasma systems, and charge-exchange beam separation. The development of sources of negative ions and their use in academic research and industry are reviewed. Physical bases and designs of surface-plasma sources of negative ions, as well as the history of their development, are presented.
This paper examines topics related to the production of H- beams of maximum brightness in surface... more This paper examines topics related to the production of H- beams of maximum brightness in surface-plasma sources. It is shown that a maximum brightness of ˜2×108 A/cm2 rad2 can be obtained in Penning geometry sources in which efficient generation of negative ions with a reduced energy of ion thermal motion in the plasma of <=0.5 eV is possible under optimized
A surface-plasma source of H- ions with a semiplanotron geometry of the discharge chamber was inv... more A surface-plasma source of H- ions with a semiplanotron geometry of the discharge chamber was investigated. The discharge was localized around the emission slit of 0.5×10 mm2, and a cylindrical cathode surface serves for geometrical focussing of H- ions. The H- beam current was up to 0.15A, normalized brightness to 108 A/cm2rad2, pulse length 200 mus and no cooling was
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