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MOPL012 |
Residual Dose Measurement and Activation of the Injection Area in the J-PARC RCS | |
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| In the 3 GeV Rapid Cycling Synchrotron (RCS) of Japan Proton Accelerator Research Complex (J-PARC), we adopted multi-turn H charge exchange injection by using stripper foil in order to achieve high power proton beam. It is therefore impossible to neglect the interaction between stripper foil and the beam. As a result, there are high residual dose measured around the stripper foil. Based on detail numerical simulations by using PHITS code, it is identified that the secondary particles produced in the nuclear reactions due to foil beam interaction caused the high residual activity around foil. In this paper, we report a detail measurement of the residual dose around the stripper foil together with the cause estimated based on simulation studies. | ||
| TUPM5X01 | Injection Painting Improvements in the J-PARC RCS | 1 |
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| In the J-PARC 3GeV RCS, the injection painting is essential method for the reduction of the space charge force. In this method, the H− beam from Linac is arranged on the large phase space area of the ring orbit during multiple turns. To implement this method, painting magnets form the time variable beam orbit. Therefore, the precise output current control of the magnet power supply is required. Because the power supply controlled by mainly feedforward signal is operated, we developed the iterative tuning method for the optimum feedforward parameter determination. As a result, we could reduce the tracking error of the current compared to before. Furthermore, to improve the accuracy of the painting area size, we applied the output readjustment additionally. Because the current monitor value of the power supply was different from the actual magnetic field due to the delay in the circuit and the leakage field, we corrected the tracking of the current based on the measured painting area size determined by the analysis of the measured COD. As a result, we achieved the precise injection painting. This talk presents these improvement results of the injection painting in the RCS. | ||
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Slides TUPM5X01 [4.127 MB] | |
| TUPM7X01 | An Experimental Plan for 400 MeV H− Stripping to Proton by Using Only Lasers in the J-PARC RCS | 1 |
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| The 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC is gradually approaching to the design operation with 1 MW beam power. Studies are ongoing for further higher beam power of 1.5 MW. The injection and extraction energy of RCS is 0.4 and 3 GeV, respectively. Lifetime of the stripper foil is the highest concern beyond 1 MW beam power. We have also already started detail studies of H− stripping to protons by using lasers. However, in order to avoid high magnetic field required in the process of laser-assisted H− stripping to protons, especially for lower H− energies, we are studying the possibilities of using only laser system for 400 MeV H− beam in the RCS. The method is a three step process, similar to that of SNS but lasers are used instead of high field magnets in the 1st (H− to H0) and 3rd step (H0* to p). A Nd:YAG laser can be properly used for both 1st and 3rd steps, where commercially available powerful Excimer laser will be used an H0 excitation in the 2nd step. Although detail R&D studies are necessary to reach to the ultimate goal, we plan to carry out an experiment in 2017. A detail of the present method, experimental schedule and the expected outcome will be presented. | ||
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Slides TUPM7X01 [3.321 MB] | |
| THAM6X01 | The Path to 1 MW: Beam Loss Control in the J-PARC 3-GeV RCS | 1 |
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| The J-PARC 3-GeV RCS started 1-MW beam test from October 2014, and successfully achieved a 1-MW beam acceleration in January 2015. The most important issues in realizing such a high power routine beam operation are control and minimization of beam loss. This talk will present the recent progress of 1-MW beam tuning, especially focusing on our approaches to beam loss issues. | ||
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Slides THAM6X01 [1.854 MB] | |