Author: Sack, M.
Paper Title Page
WEPAB351 Requirements for an Inductive Voltage Adder as Driver for a Kicker Magnet with Short Circuit Termination 3521
 
  • J. Ruf, M.J. Barnes, T. Kramer
    CERN, Geneva 23, Switzerland
  • M. Sack
    KIT, Karlsruhe, Germany
  
  At CERN pulse gen­er­a­tors based on Thyra­tron switches and SF6 gas filled pulse form­ing lines, used for dri­ving kicker mag­nets, are to be re­placed with semi­con­duc­tor tech­nol­ogy. Pre­lim­i­nary in­ves­ti­ga­tions show the in­duc­tive volt­age adder is suit­able as a pulse gen­er­a­tor for this ap­pli­ca­tion. To in­crease the mag­netic field with­out rais­ing the sys­tem volt­age, a short-cir­cuit ter­mi­na­tion is often ap­plied to a kicker mag­net. Be­cause of the elec­tri­cal length of a trans­mis­sion line mag­net, wave prop­a­ga­tion needs to be con­sid­ered. To allow for the wave­front re­flected from the short-cir­cuit ter­mi­na­tion back to the gen­er­a­tor, a novel ap­proach for an in­duc­tive adder ar­chi­tec­ture has been in­ves­ti­gated. It is based on a mod­i­fied gen­er­a­tor in­ter­face, cir­cu­lat­ing the cur­rent back into the load, until the stored en­ergy is ab­sorbed at the end of the pulse. This ap­proach al­lows for a smaller mag­netic core size com­pared to a con­ven­tional de­sign with a matched load. More­over, it en­ables more en­ergy-ef­fi­cient op­er­a­tion in­volv­ing smaller stor­age ca­pac­i­tors. This paper sum­ma­rizes the con­cep­tual de­sign fea­tures and fur­ther­more gives an overview of the pa­ra­me­ter space for pos­si­ble ap­pli­ca­tions at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB351  
About • paper received ※ 18 May 2021       paper accepted ※ 11 June 2021       issue date ※ 17 August 2021  
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THPAB340 Sub-Nanosecond Switching of HV SiC MOS Transistors for Impact Ionisation Triggering 4454
 
  • V. Senaj, T. Kramer, A.A. del Barrio Montañés
    CERN, Geneva 23, Switzerland
  • M. Sack
    KIT, Karlsruhe, Germany
  
  Pulse gen­er­a­tors with multi kV/kA pulses are nec­es­sary for the par­ti­cle ac­cel­er­a­tor en­vi­ron­ment for beam trans­fer mag­nets. Tra­di­tion­ally these gen­er­a­tors are using thyra­trons - until re­cently the only switches ca­pa­ble of switch­ing such pulses within tens of ns. There is a strong de­mand to re­place thyra­trons with semi­con­duc­tor switches to avoid their fu­ture ob­so­les­cence. Very promis­ing can­di­dates are com­po­nents from the fam­ily of fast ion­iza­tion dynis­tors trig­gered by im­pact ion­iza­tion. Their sub-nanosec­ond switch­ing time and ex­treme cur­rent den­si­ties can pro­vide per­for­mances su­pe­rior to that of thyra­trons. Re­cent in­ves­ti­ga­tions showed that im­pact ion­iza­tion trig­ger­ing is fea­si­ble also in cheap in­dus­trial thyris­tors. The main issue is the gen­er­a­tion of trig­ger­ing pulses with slew rates in the multi kV/ns re­gion and with the re­quired out­put cur­rent for charg­ing the par­a­sitic ca­pac­i­tance of the thyris­tor. We pre­sent an ap­proach of gen­er­at­ing > 1 kV/ns pulses by ul­tra-boosted gate dri­ving of HV SiC MOS tran­sis­tors. We found that the MOS life­time under these ex­treme trig­ger­ing con­di­tions can still reach more than 108 pulses, enough for kicker gen­er­a­tor ap­pli­ca­tions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB340  
About • paper received ※ 18 May 2021       paper accepted ※ 01 July 2021       issue date ※ 27 August 2021  
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