Author: Winklehner, D.
Paper Title Page
MOPAB159 Matching of an RFQ and Multicusp Ion Source with Compact LEBT 546
 
  • L.H. Waites, J.M. Conrad, J. Smolsky, D. Winklehner
    MIT, Cambridge, Massachusetts, USA
 
  Funding: NSF provided funding for RFQ-DIP project, Draper Laboratory provided fellowship for graduate studnets
The Iso­DAR pro­ject is a neu­trino ex­per­i­ment that re­quires a high cur­rent H2+ beam at 60 MeV/amu, which will be pro­duced by a cy­clotron. A crit­i­cal as­pect of the de­sign is the in­jec­tion, which com­prises an ion source, a com­pact low en­ergy beam trans­port sec­tion (LEBT), and a ra­dio-fre­quency quadru­pole (RFQ) buncher em­bed­ded in the cy­clotron yoke. The LEBT is op­ti­mized to match the de­sired input Twiss pa­ra­me­ters of the RFQ. Here we re­port on the lat­est re­sults from the ion source com­mis­sion­ing, and on the de­sign and op­ti­miza­tion of the LEBT with match­ing to the RFQ. With this ion source, we have demon­strated a 76% H2+ frac­tion at a cur­rent den­sity of 11 mA/cm2 in DC mode. The de­sign of the LEBT in­cludes a chop­per, steer­ing el­e­ments, and fo­cus­ing el­e­ments, to achieve the de­sired match­ing, which ac­cord­ing to our sim­u­la­tions leads to ~95% trans­mis­sion from the ion source to the exit of the RFQ.
 
poster icon Poster MOPAB159 [0.851 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB159  
About • paper received ※ 15 May 2021       paper accepted ※ 24 June 2021       issue date ※ 13 August 2021  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPAB160 Tools for the Development and Applications of the IsoDAR Cyclotron 550
 
  • L.H. Waites, J.R. Alonso, J.M. Conrad, D. Koser, D. Winklehner
    MIT, Cambridge, Massachusetts, USA
 
  Funding: NSF provided funding for the RFQDIP project, Draper laboratory provided a fellowship for the graduate student
The Iso­DAR cy­clotron is a 60 MeV cy­clotron de­signed to out­put 10mA of pro­tons in order to be a dri­ver for a neu­trino ex­per­i­ment. How­ever, this high power can be used in other use­ful and im­por­tant ap­pli­ca­tions out­side of par­ti­cle physics. The Iso­DAR cy­clotron ac­cel­er­ates H2+, which al­lows the beam to be highly ver­sa­tile and im­por­tant for the de­vel­op­ment of high-power tar­gets. This could help al­le­vi­ate a huge bot­tle­neck in the med­ical iso­tope com­mu­nity. Iso­DAR could also be used for the de­vel­op­ment of ma­te­ri­als. The ac­cel­er­a­tor sys­tem uses many new tools, in­clud­ing novel meth­ods of ap­ply­ing ma­chine learn­ing, as well as sev­eral of the uses of this new tech­nol­ogy. With these ap­pli­ca­tions and tools, the Iso­DAR cy­clotron can have an im­por­tant im­pact on the ac­cel­er­a­tor, med­ical, and physics com­mu­ni­ties.
 
poster icon Poster MOPAB160 [0.424 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB160  
About • paper received ※ 15 May 2021       paper accepted ※ 24 June 2021       issue date ※ 13 August 2021  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUXB07 High-Current H2+ Beams from a Compact Cyclotron using RFQ Direct Injection 1301
 
  • D. Winklehner, J.M. Conrad, D. Koser, J. Smolsky, L.H. Waites
    MIT, Cambridge, Massachusetts, USA
 
  Funding: This work was supported by NSF grants PHY-1505858 and PHY-1626069.
For the Iso­DAR neu­trino ex­per­i­ment, we have de­vel­oped a com­pact and cost-ef­fec­tive cy­clotron-based dri­ver to pro­duce high cur­rent beams (cw pro­ton beam cur­rents of >10 mA at 60 MeV). This is a fac­tor of 4 higher than the cur­rent state-of-the-art for cy­clotrons and a fac­tor of 10 com­pared to what is com­mer­cially avail­able. All areas of physics that call for high cw cur­rents can greatly ben­e­fit from this re­sult; e.g. par­ti­cle physics, med­ical iso­tope pro­duc­tion, and en­ergy re­search. This in­crease in beam cur­rent is pos­si­ble in part be­cause the cy­clotron is de­signed to in­clude and use vor­tex-mo­tion, al­low­ing clean ex­trac­tion. Such a de­sign process is only pos­si­ble with the help of high-fi­delity codes, like OPAL. An­other nov­elty is the use of an RFQ em­bed­ded in the cy­clotron yoke to bunch the beam dur­ing axial in­jec­tion. Fi­nally, using H2+ re­lieves some of the space charge con­straints dur­ing in­jec­tion. In this paper, we will give an overview of the pro­ject and then focus on the de­sign and sim­u­la­tions of the cy­clotron it­self. We will de­scribe the physics, com­pu­ta­tional tools, and sim­u­la­tion re­sults. At the end, we will de­scribe how we are in­clud­ing ma­chine learn­ing in the sim­u­la­tions.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXB07  
About • paper received ※ 27 May 2021       paper accepted ※ 22 July 2021       issue date ※ 31 August 2021  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPAB195 Design and Optimization of a Low Frequency RF-Input Coupler for the IsoDAR RFQ 3081
 
  • M.P. Sangroula, J.M. Conrad, D. Winklehner
    MIT, Cambridge, Massachusetts, USA
  • M. Schuett
    BEVATECH, Frankfurt, Germany
 
  Funding: The RFQ-DIP project is supported by National Science Foundation grant \# PHY-1626069 and the Heising-Simons Foundation.
The Iso­tope De­cay-At-Rest ex­per­i­ment (Iso­DAR) is a pro­posed un­der­ground ex­per­i­ment which is ex­pected to be a de­fin­i­tive search for ster­ile neu­tri­nos. Iso­DAR uses an es­pe­cially de­signed low-fre­quency spilt-coax­ial radio fre­quency quadru­pole (RFQ) to ac­cel­er­ate H2+ ions di­rectly from the ion source into the main cy­clotron ac­cel­er­a­tor. This paper mainly fo­cuses on the de­sign and op­ti­miza­tion of a low fre­quency (32.8 MHz) RF-in­put cou­pler for the Iso­DAR RFQ. Start­ing with a basic de­sign, we de­ter­mine its ap­pro­pri­ate po­si­tion for this cou­pler in the RFQ. Fi­nally, we op­ti­mized the de­sign to lower the input power with­out com­pro­mis­ing the cou­pling ef­fi­ciency.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB195  
About • paper received ※ 21 May 2021       paper accepted ※ 30 June 2021       issue date ※ 29 August 2021  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPAB202 Thermal Analysis of a Compact Split-Coaxial CW RFQ for the IsoDAR RFQ-DIP 3097
 
  • D. Koser, J.M. Conrad, D. Winklehner
    MIT, Cambridge, Massachusetts, USA
  • H. Podlech, U. Ratzinger, M. Schuett
    BEVATECH, Frankfurt, Germany
 
  The RFQ di­rect in­jec­tion pro­ject (RFQ-DIP) for the neu­trino physics ex­per­i­ment Iso­DAR aims at an ef­fi­cient in­jec­tion of a high-cur­rent H2+ beam into the ded­i­cated 60 MeV dri­ver cy­clotron. There­fore, it is in­tended to use a com­pact 32.8 MHz RFQ struc­ture of the split-coax­ial type as a pre-buncher. To de­ter­mine the ther­mal elon­ga­tion of the 1.4 m long elec­trode rods as well as the ther­mal fre­quency de­tun­ing of the RF struc­ture at a max­i­mum nom­i­nal power load of 3.6 kW, an ex­ten­sive ther­mal and struc­tural me­chan­i­cal analy­sis using COM­SOL Mul­ti­physics was con­ducted. The water heat­ing along the cool­ing chan­nels as well as the prop­er­ties of heat trans­fer from the cop­per struc­ture to the cool­ing water were taken into ac­count, which re­quired CFD sim­u­la­tions of the cool­ing water flow in the tur­bu­lent regime. Here we pre­sent the meth­ods and re­sults of the so­phis­ti­cated ther­mal and struc­tural me­chan­i­cal sim­u­la­tions using COM­SOL and pro­vide a com­par­i­son to more sim­plis­tic sim­u­la­tions con­ducted with CST Stu­dio Suite.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB202  
About • paper received ※ 20 May 2021       paper accepted ※ 01 July 2021       issue date ※ 14 August 2021  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPAB203 RFQ Beam Dynamics Optimization Using Machine Learning 3100
 
  • D. Koser, J.M. Conrad, L.H. Waites, D. Winklehner
    MIT, Cambridge, Massachusetts, USA
  • A. Adelmann, M. Frey, S. Mayani
    PSI, Villigen PSI, Switzerland
 
  To ef­fi­ciently in­ject a high-cur­rent H2+ beam into the 60 MeV dri­ver cy­clotron for the pro­posed Iso­DAR pro­ject in neu­trino physics, a novel di­rect-in­jec­tion scheme is planned to be im­ple­mented using a com­pact ra­dio-fre­quency quadru­pole (RFQ) as a pre-buncher, being par­tially in­serted into the cy­clotron yoke. To op­ti­mize the RFQ beam dy­nam­ics de­sign, ma­chine learn­ing ap­proaches were in­ves­ti­gated for cre­at­ing a sur­ro­gate model of the RFQ. The re­quired sam­ple datasets are gen­er­ated by stan­dard beam dy­nam­ics sim­u­la­tion tools like PARMTEQM and RFQ­Gen or more so­phis­ti­cated PIC sim­u­la­tions. By re­duc­ing the com­pu­ta­tional com­plex­ity of multi-ob­jec­tive op­ti­miza­tion prob­lems, sur­ro­gate mod­els allow to per­form sen­si­tiv­ity stud­ies and an op­ti­miza­tion of the cru­cial RFQ beam out­put pa­ra­me­ters like trans­mis­sion and emit­tances. The time to so­lu­tion might be re­duced by up to sev­eral or­ders of mag­ni­tude. Here we dis­cuss dif­fer­ent meth­ods of sur­ro­gate model cre­ation (poly­no­mial chaos ex­pan­sion and neural net­works) and iden­tify pre­sent lim­i­ta­tions of sur­ro­gate model ac­cu­racy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB203  
About • paper received ※ 20 May 2021       paper accepted ※ 01 July 2021       issue date ※ 30 August 2021  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPAB167 Technical Design of an RFQ Injector for the IsoDAR Cyclotron 4075
 
  • H. Höltermann, D. Koser, B. Koubek, H. Podlech, U. Ratzinger, M. Schuett, M. Syha
    BEVATECH, Frankfurt, Germany
  • J.M. Conrad, J. Smolsky, L.H. Waites, D. Winklehner
    MIT, Cambridge, Massachusetts, USA
 
  For the Iso­DAR (Iso­tope De­cay-At-Rest) ex­per­i­ment, a high in­ten­sity (10 mA CW) pri­mary pro­ton beam is needed. To gen­er­ate this beam, H2+ is ac­cel­er­ated in a cy­clotron and stripped into pro­tons after ex­trac­tion. An RFQ, par­tially em­bed­ded in the cy­clotron yoke, will be used to bunch and ax­i­ally in­ject H2+ ions into the main ac­cel­er­a­tor. The strong RFQ bunch­ing ca­pa­bil­i­ties will be used to op­ti­mize the over­all in­jec­tion ef­fi­ciency. To keep the setup com­pact the dis­tance be­tween the ion source and RFQ can be kept very short as well. In this paper, we de­scribe the tech­ni­cal de­sign of the RFQ. We focus on two crit­i­cal as­pects: 1. The use of a split-coax­ial struc­ture, ne­ces­si­tated by the low fre­quency of 32.8 MHz (match­ing the cy­clotron RF) and the de­sired small tank di­am­e­ter; 2. The high cur­rent, CW op­er­a­tion, re­quir­ing a good cool­ing con­cept for the RFQ tank and vanes.  
poster icon Poster THPAB167 [2.162 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB167  
About • paper received ※ 14 May 2021       paper accepted ※ 27 July 2021       issue date ※ 21 August 2021  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)