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ion sourceUeno, Akira; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Shinto, Katsuhiro; Oguri, Hidetomo
AIP Conference Proceedings 2052, p.050003_1 - 050003_7, 2018/12
Times Cited Count：2 Percentile：71.98(Physics, Applied)In order to specify the beam intensity bottlenecks of the J-PARC cesiated RF-driven H ion source, the extraction and acceleration voltages (V
and V
) higher than the design values of 10 kV and 40 kV were examined. A 100 mA beam, whose about 93 mA has transverse emittances used for a common RFQ design, was stably operated with a duty factor of 5% (1 ms 
50 Hz) by using the V and V of 12.4 kV and 49.6 kV, respectively. This breakthrough with important information on the space-charge limited bottlenecks in the extraction and acceleration gaps will derive the optimal electrode shapes for the source operated with a beam intensity higher than 100 mA and realize the next generation benchmark H ion source for high intensity and high energy H LINACs.
Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Ikegami, Kiyoshi*; Takagi, Akira*; Namekawa, Yuya*; Ueno, Akira; Oguri, Hidetomo
AIP Conference Proceedings 2052, p.050002_1 - 050002_7, 2018/12
Times Cited Count：6 Percentile：93.93(Physics, Applied)In the 2017/2018 campaign, the J-PARC cesiated rf-driven negative hydrogen (H
) ion source producing H beam with the beam current of 47 mA accomplished three long-term operations more than 2,000 hours without any serious issues. On the final day of this campaign, the ion source produced an H beam current of 72 mA so that the linac commissioning group could demonstrate the beam current of 60 mA at the linac exit. We are also conducting an endurance test of a J-PARC-made antenna at a test bench. The antenna achieved the operation time approximately 1,400 hours.
ion sourceShibata, Takanori*; Takagi, Akira*; Shinto, Katsuhiro; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Nammo, Kesao*; Oguri, Hidetomo; Naito, Fujio*
no journal, ,
For the application of bias voltage in J-PARC Radio Frequency (RF) negative ion source, characteristics of the voltage variation on the plasma electrode are investigated with different RF plasma conditions. A continuous 30 MHz RF power up to 10 - 100 W and a pulsed 2 MHz RF power up to 5 - 20 kW are injected from internal RF antenna coil. In each case, time structure of the voltage between the plasma electrode and the isolated source chamber is measured by voltage probe with different measurement resistances. Behavior of the measured voltage differs strongly whether the RF plasma is in the E mode phase by 30 MHz RF injection or in the H mode phase by 2 MHz RF injection. The results suggest that formation of capacitively coupled electric field and inductively coupled magnetic field decide the positive and the negative fluxes coming into the chamber wall. Under the same plasma condition as in the J-PARC user operation, peak value of the voltage between the source chamber and the plasma electrode is around 60 - 80 V and frequency of the voltage is a combination of 2 MHz and 30 MHz. For the continuous bias voltage application on the plasma electrode, additional distributed constant circuit to cancel these voltage oscillation and high voltage bias power supply are required.
