STABILIY EVALUATION WITH LONG FB LOOP DELAY IN THE ACS CAVITY RF CONTROL FOR THE J-PARC 400-MeV LINAC Tetsuya Kobayashi 1 Japan Atomic Energy Agency (JAEA) 2-4 Shirakata-Shirane, Tokai, Naka, Ibaraki, 319-1195 Abstract For 400-MeV upgrade of the J-PARC Linac. ACS (Annular Coupled Structure) cavities, which are driven by 972- MHz RF, will be installed. The ACS cavity has complicated structure. Its Q-value is very low and the operation frequency is tree times high in comparison with that of the SDTL cavity. So the stabilizing control of the ACS accelerating field will be more difficult than present RF system. Further more the chopped beam loading compensation is required. Especially, a debuncher will be located very far from the klystron, then the feedback loop delay will be about 1.5 μs. This presentation will show the simulation results of the feedback control of the ACS cavity field including long loop delay and the effect of the chopped beam loading. J-PARC400MeVK<*70& FBLQCÇ}& ACS®¡ RFd£½\ 1 E-mail: [email protected] J-PARC T§x±)©xÑyfÅq % [1] xc 400MeV K<*70 3Gev 2 P0N:NPÙ RCS: Rapid Cycling Synchrotron Úi 50GeV 2P0N:NPÙ MR: Main Ring Ú 3 ¬Ö fÅq'&¤tK<*7 0 181MeV fÅÙfÅo Ü 324MHz Ú RCS `~)·& 400MeV -=L/Qv'&¼¦& K<*70 400MeV vfÅ o 972MHz ACS Ù Annular Coupled Structure Ú® ¡ [2] 21 kÃf'&' RF do 3 ]×R ACS ®¡ÆºÓ¿¶ Q ^ 8000 «ZÙ DTL ° 20000 Ú! FB d 324MHz RF 248F$%hX&£ S¢9P>6GQÙ RCS `~@QF¾¥ ACS ®¡Ú¸´#Ël$%®¡0 J,4:NP 100m WR«Ô'&% FB LQCÇ"Ä° 3 ]& ACS ®¡×o FB d£!ÎLQ CÇ)m!2EHMQ2IP½\)· 'un& LLRF K<*70xAQ0 50mA 500μs D0 N?L4@QF) 25Hz Ùx 50Hz Ú³%Âf ÅD0N?L4K<*70R¢Ù MEBT Ú RF 6I7?Q$ RCS oroÙ RF >17: ° 1MHz Úl(6I7C'VÐ? L4ÆÙ6I7C;@QFÚ& RCS `~@QFAQ0Õ¢ 50mA Èg Í%ÙΔ p/p Ú 0.1% WS&»' &x×pÀ@QFfÅ fÅÕ§z{"Ì»µÛ% Yªwg'' 1 1% Wa» '&')|¤&!ZÕe×o Ù LLRF Ú d FPGA $&935LB+Q;>70 Ù FB Úd248FϨ' [3] B+Q;B. OQ;Ù FF Úd)[¥&@QF¿¶¹_ }& ACS ®¡6I7C;@Q FÆ$&fÅÕ§wg"x% !@QF¿¶¹_µ"»& [4][5] ¤t 181MeV fÅ 324MHz fÅ®¡ Ù SDTL ¯Ú 24 U|Ò@QFfÅÈÁ fÅÕ§z{Yª'' 0.2 0.2 Ø«)É&²! b¤×@QF) RCS `~&j µ& sÛÜK<*70`~*Q0ÊDB2 Proceedings of the 7th Annual Meeting of Particle Accelerator Society of Japan (August 4-6, 2010, Himeji, Japan) -1082-