摘要:

Recent progress of polarized ion sources has been enormous. Polarized H−beams of more than 1 mA in dc/pulsed beam operation have been realized. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146698

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The TRIUMF dc optically pumped polarized H−ion source (OPPIS) produces a 200 &mgr;A dc H−current at 85% polarization within a normalized emittance (90%) of 0.8 &pgr; mm mrad, for operation at the TRIUMF cyclotron. As a result of development of the electron cyclotron resonance primary proton source, a 1.6 mA dc polarized H−current is produced within a normalized emittance of 2 &pgr; mm mrad, suitable for high energy accelerators. The OPPIS has also been developed for use in a parity nonconservation experiment which has very severe limits on permissible helicity‐ correlated changes in beam current and energy. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146699

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The Moscow Institute for Nuclear Research atomic‐beam type source of polarized negative hydrogen ions is described. The production of H−ions is based on the resonant charge exchange of polarized thermal hydrogen atoms and D−ions in deuterium plasma. Improvements in the D−plasma source are outlined. The polarized source produces a pulsed H−beam with a peak current up to 1 mA and a pulse duration of 180 &mgr;s at a repetition rate of 10 Hz. The normalized emittance for 90% of the beam particles is 1.8 &pgr; mm mrad. The polarimeter of low energy H−ions is also described. The polarization of the H−ions was measured to be 0.87±0.02. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146700

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Powerful cw proton linear accelerators (100 mA at 0.5–1.0 GeV) are being proposed for spallation neutron‐source applications. A 75‐keV, 110‐mA dc proton injector using a microwave ion source is being tested for these applications. It has achieved 80‐keV, 110‐mA hydrogen‐ion‐beam operation. Video and dc beam‐current toroid diagnostics are operational, and an EPICS control system is also operational on the 75‐keV injector. A technical base development program has also been carried out on a 50‐keV injector obtained from Chalk River Laboratories, and it includes low‐energy beam transport studies, ion source lifetime tests, and proton‐fraction enhancement studies. Technical base results and the present status of the 75‐keV injector will be presented. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146701

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The radio‐frequency (rf) driven multicusp source was originally developed for use in the Superconducting Super Collider injector. It has been demonstrated that the source can meet the H−beam current and emittance requirements for this application. By employing a porcelain‐coated antenna, a clean plasma discharge with very long‐life operation can be achieved. Today, the rf source is used to generate both positive and negative hydrogen ion beams and has been tested in various particle accelerator laboratories throughout the world. Applications of this ion source have been extended to other fields such as ion beam lithography, oil‐well logging, ion implantation, accelerator mass spectrometry and medical therapy machines. This paper summarizes the latest rf ion source technology and development at the Lawrence Berkeley National Laboratory. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146702

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The neutron scattering community has endorsed the need for a high‐power (1–5 MW) accelerator‐driven source of neutrons for materials research. Properly configured, the accelerator could produce very short (submicrosecond) bursts of cold neutrons, said time structure offering advantages over the continuous flux from a reactor. The recent cancellation of the ANS reactor project has increased the urgency to develop a comprehensive strategy based on the best technological scenarios. Studies to date have built on the experience from ISIS (the 160 kW source in the UK), and call for a high‐current (∼100 mA peak) H−source‐linac combination injecting into one or more accumulator rings in which beam may be further accelerated. The 1–5 GeV proton beam is extracted in a single turn and brought to the target‐moderator stations. The high current, high duty factor, high brightness and high reliability required of the ion source present a very large challenge to the ion source community. The Workshop reported on here, held in Berkeley in October 1994, analyzed in detail the source requirements for proposed accelerator scenarios, the present performance capabilities of different H−source technologies, and identified necessary R&D efforts to bridge the gap. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146703

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A 15 mA dc H−multicusp source has been developed for injection into a TR30 cyclotron. This source is also used with a 900 kV tandem accelerator to obtain 10 mA protons at 1.8 MeV. The program is an extension of the 5–7 mA dc H−cusp source developed at TRIUMF during 1989–1990. Major efforts include the search for the optimal filament materials, shape, and location; comparison of cusp line confinement and magnetic filtering of electrons at the extraction region; optimization of extraction lense configuration; and upgrading of vacuum and power systems capability. The source is noncesiated and the maximum arc power available is only 5 kW. After the H−beams pass through an electron suppression grid and a 20 mm collimator, we obtained 15 mA with 0.66 &pgr; mm mrad 4 rms normalized emittance. At this output thee/Hratio was about 4. The best normalized emittance occurs around 5–7 mA, having a value of 0.37 &pgr; mm mrad. Further development in the near future is planned using cesium and multiple apertures in the hope of increasing dc H−currents to 30 mA while holding the normalized emittance below 0.75 &pgr; mm mrad. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146704

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We will describe the operation of a cw rf driven multicusp ion source designed for extraction of high current hydrogen and deuterium beams. The source is driven at 2 MHz by a 2.5 turn induction antenna immersed in the plasma. Bare stainless‐steel and porcelain‐coated Cu antennas have been used. The plasma load is matched to the rf generator by a variable tapN:1 transformer isolated to 46 kV, and an LC network on the secondary. With H2gas the source can be operated at pressures between 5 and 60 mT with power reflection coefficients <0.01. The extracted ion current density with a porcelain‐coated antenna is approximately given by 35 mA/cm2/kW with an 80 G dipole filter field for input powers from 3.5 to 6.6 kW. The current density remained constant for operation with a 6 and an 8 mm aperture. The source has been operated for 260 h at 3.6 kW with a single‐porcelain‐coated antenna. Mass spectrometer measurements of the extracted beam at this power show a species mix for H+:H+2:H+3:OH+of 0.49: 0.04: 0.42: 0.04. The calculated beam divergence using the IGUN code is compared with the measured divergence from an electrostatic sweep emittance scanner designed for high‐power cw beam diagnostics. Phase space measurements at 40 kV and 23 mA beam current result in a normalized rms emittance of 0.09 &pgr; mm mrad. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147243

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

To evaluate the performance of a high current H−rf‐driven volume ion source, the Superconducting Super Collider ion source was modified to accommodate a set of cesium dispensers so that a trace amount of cesium could be introduced into the plasma grid collar. A plasma grid heater element controls the temperature of the cesiated surfaces and the rate of cesium dispensation. With this modification, beam currents in excess of 100 mA and electron to H−current ratios close to one have been observed. In contrast, the uncesiated source provided 30 mA of H−beam with ane/H−ratio ≥25. In both cases the source was operated with a 100 &mgr;s beam pulse width at a 10 Hz repetition rate, and an extraction voltage of 35 kV. This cesium enhanced source is a strong candidate for use in high current H−accelerators. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146705

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The motion of a charged particle in a crossed rf field and dc magnetic field describes the occurrence of resonance (increase of the energy gained by the particle between collisions) which causes low breakdown voltage, higher plasma intensity, and higher extracted ion current. The resonance in the microwave discharge is essential for plasma electron heating. The development line in both ECRIS’s and RFIS’s includes an increase of the electron population in the discharge to intensify the plasma and increase the extracted ion current; plasma cooling with the use of electron injection or gas mixing increases the lifetime of the ions in the plasma allowing for multiple ionization collision and increase of the highly charged ion species. Adaptation of both electrical and geometrical properties of these sources can lead to obtaining lower beam emittance. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146706

出版商:AIP    

年代:1996

数据来源: AIP