Cesiated surface H− ion source: optimization studies. (11th January 2017)
- Record Type:
- Journal Article
- Title:
- Cesiated surface H− ion source: optimization studies. (11th January 2017)
- Main Title:
- Cesiated surface H− ion source: optimization studies
- Authors:
- Ueno, Akira
- Abstract:
- Abstract: The H − ion beam intensity required for high-energy and high-intensity proton accelerators is continuously increasing. The required 95%-beam transverse normalized root mean square emittance ( ε 95%rnms x / y ) of the beam is around 0.25 π mm mrad for all accelerators. The Japan Proton Accelerator Complex (J-PARC) 400 MeV linear accelerator (LINAC) succeeded in accelerating the world's highest-class H − ion beam of 50 mA with a cesiated RF-driven H − ion source. This was achieved by increasing the beam brightness through the following measures: (1) 45°-tapered plasma electrode (PE) with a 16 mm thickness to increase beam intensity by 56%, (2) continuous-wave igniter plasma driven by 50 W 30 MHz RF to reduce hydrogen pressure in the plasma chamber (PCH) by 50% and beam loss in low-energy beam transport by 12%, compared with that by the commonly used 300 W 13.56 MHz RF, (3) axial magnetic-field correction around the PE beam aperture to increase beam intensity by a maximum of 15%, (4) operation at a low PE temperature ( T PE ) of about 70 °C to reduce ε 95%nrms x / y by 27%, (5) suitable beam apertures of the plasma and the extraction electrodes to increase beam intensity by a maximum of 7% and to reduce ε 95%nrms x / y by more than 4%, (6) argon/nitrogen elimination and 39% filter-field reduction to reduce ε 95%nrms x / y by 9% and the required 2 MHz RF power by around 30%, (7) eight-hours conditioning with a 50 kW 2 MHz RF and a 5% (1 ms × 50 Hz) duty factor toAbstract: The H − ion beam intensity required for high-energy and high-intensity proton accelerators is continuously increasing. The required 95%-beam transverse normalized root mean square emittance ( ε 95%rnms x / y ) of the beam is around 0.25 π mm mrad for all accelerators. The Japan Proton Accelerator Complex (J-PARC) 400 MeV linear accelerator (LINAC) succeeded in accelerating the world's highest-class H − ion beam of 50 mA with a cesiated RF-driven H − ion source. This was achieved by increasing the beam brightness through the following measures: (1) 45°-tapered plasma electrode (PE) with a 16 mm thickness to increase beam intensity by 56%, (2) continuous-wave igniter plasma driven by 50 W 30 MHz RF to reduce hydrogen pressure in the plasma chamber (PCH) by 50% and beam loss in low-energy beam transport by 12%, compared with that by the commonly used 300 W 13.56 MHz RF, (3) axial magnetic-field correction around the PE beam aperture to increase beam intensity by a maximum of 15%, (4) operation at a low PE temperature ( T PE ) of about 70 °C to reduce ε 95%nrms x / y by 27%, (5) suitable beam apertures of the plasma and the extraction electrodes to increase beam intensity by a maximum of 7% and to reduce ε 95%nrms x / y by more than 4%, (6) argon/nitrogen elimination and 39% filter-field reduction to reduce ε 95%nrms x / y by 9% and the required 2 MHz RF power by around 30%, (7) eight-hours conditioning with a 50 kW 2 MHz RF and a 5% (1 ms × 50 Hz) duty factor to reduce ε 95%nrms x / y by 15%, and (8) slight water molecules (H2 Os) feeding in hydrogen to avoid ε 95%nrms x / y increase by 72% and divergence angle expansion by 50%. In the studies, we investigated principally the 66 mA H − ion beams extracted from the source in order to achieve a 50 mA beam at the J-PARC LINAC exit regardless of the beam's brightness. Consequently, the source can produce the required beam for a 60 mA J-PARC LINAC operation, since the world's brightest-class beam with the ε 95%nrms x / y of 0.23 π mm mrad and beam intensity of 66 mA is successfully produced through the above measures. … (more)
- Is Part Of:
- New journal of physics. Volume 19:Number 1(2017:Jan.)
- Journal:
- New journal of physics
- Issue:
- Volume 19:Number 1(2017:Jan.)
- Issue Display:
- Volume 19, Issue 1 (2017)
- Year:
- 2017
- Volume:
- 19
- Issue:
- 1
- Issue Sort Value:
- 2017-0019-0001-0000
- Page Start:
- Page End:
- Publication Date:
- 2017-01-11
- Subjects:
- negative H ion source -- RF-driven ion source -- cesiated surface ion source
Physics -- Periodicals
Physics
Periodicals
530.05 - Journal URLs:
- http://iopscience.iop.org/1367-2630 ↗
http://njp.org/index.html ↗
http://ioppublishing.org/ ↗ - DOI:
- 10.1088/1367-2630/aa52e3 ↗
- Languages:
- English
- ISSNs:
- 1367-2630
- Deposit Type:
- Legaldeposit
- View Content:
- Available online (eLD content is only available in our Reading Rooms) ↗
- Physical Locations:
- British Library DSC - BLDSS-3PM
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