DREEBIT EBIS/T FOR APPLICATIONS IN ACCELERATOR PHYSICS

M. Schmidt∗, A. Thorn, DREEBIT GmbH, Dresden, GermanyG. Zschornack, Technische Universitat Dresden, Dresden, Germany

AbstractElectron Beam Ion Sources and Traps (EBIS/T) pro-

vide light up to heavy ions of low up to high chargestates for various applications in accelerator physics suchas medical particle therapy and charge breeding. Beside thewell-known but quiet costly superconducting EBIS/T typesystems compact and permanent magnet-operated EBIS/Tfrom the DREEBIT GmbH are available, favorable for low-budget projects. Moreover, the ”flagship” of the DREEBITion source family, the superconducting EBIS-SC featuresoperating parameters comparable to the complex and ex-pensive systems in the EBIS/T community.

HIGHLY CHARGED IONS

PropertiesHighly charged ions yield interesting properties, in par-

ticular for accelerator physics. They feature a very effi-cient acceleration potential since the kinetic energy gainincreases linearly with the charge state for electrostatic ac-celerator and even quadratically with the charge state forcircular accelerators. Furthermore, the potential energy ofhighly charged ions leads to high power deposition into sur-faces connected with higher secondary particle emission ation solid interactions.

ProductionHowever, the production of highly charged ions (HCIs)

has led to different technological approaches, such as ionstripping in ion accelerator structures, ECR ion sources,laser ion sources and Electron Beam Ion Sources/Traps(EBIS/T). Beside the mentioned technologies EBIS/T sys-tems have proved as reliable and stable working sources ofHCIs of the highest charge states.

EBIS/TEBIS/T ionize initially neutrals and low charged ions in

magnetically compressed high-dense electron beams up tohigh and very high charge states. Already small amountsof bare uranium ions have been produced.Normally, such EBIS/T facilities feature special, so-phisticated and complex laboratory installations of thesuperconducting ion source type.There are only two suppliers in the world offering com-mercial EBIS/T systems. One of them is the DREEBITGmbH Dresden (Germany) marketing a whole family ofEBIS/T systems.

∗mike.schmidt@dreebit.com

The room-temperature Dresden EBIS/T with permanentmagnets feature operating parameters which suit mostof the user requirements at by far lower initial as wellas maintenance costs (see Fig. 1). In addition, in orderto satisfy the need for increased ion output, a liquidhelium free superconducting EBIS (Dresden EBIS-SC)with closed-cycle refrigerator technology is availablecomplementing the ion source portfolio of the company(see Fig. 2).

USER-SPECIFIC ION IRRADIATIONFACILITY

Based on its ion source knowledge the DREEBIT GmbHhas designed and comissioned several customer-specificion irradition facilities equipped with Dresden EBIS/Tsystems (see Fig. 3). The facilities are complemented withthe necessary ion optics and ion diagnostics such as Einzellenses, deflectors, quadrupol beam bender, accel/decellens systems, Wien filter, Pepper-Pot-Emittance Meter,Retarding-Field Analyzer, Faraday cups. Individual targetchamber and target transfer systems. In dependenceon the user need different configurations of ion sourcesand beamline equipment as mentioned above have beenaccomplished.

Figure 1: Room-Temperature EBIS/T.

APPLICATIONSEBIS/T systems have been succesfully operated in low

energy beamlines so far. In order to extend the applicationpotential investigations on charge breeding as well as inmedical particle therapy have been done.

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170 Ion Sources, Traps, and Charge Breeding

Figure 2: EBIS-SC.

Figure 3: Ion Irradiation Facility L.

Charge BreedingCharge breeding via external injection in EBIS/T com-

plements the portfolio of available elements for the pro-duction of highly charged ions. In particlular the produc-tion of short-living radioactive isotops and their efficientpost-acceleration as well as the exact mass determinationof them makes efficient charge breeding necessary. [1].Thereby the species of interest is produced outside the ionsource and subsequently injected into the EBIS/T, e.g. asan beam of low charged ions. In the EBIS/T charge breed-ing converts the low charged ions to highly charged ions.Proving the charge breeding ability and efficiency experi-ments with gold have been done with a Dresden EBIS-A[2]. A liquid metal alloy ion source was used for producinglow charged gold ions extracting them and subsequentlyinjecting them into the EBIS-A for charge-breeding and re-extraction after ionizing (see Fig. 4).

Medical Particle TherapyCancer is the second most common cause of death in

the industrial nations. Hence every 3rd person will con-front some kind of cancer in its life. About 45 percent ofcancer patients can be treated, mainly by surgery and ra-diation therapy, respectively [3]. Thereby hadron therapywith protons and carbon ions is the second most successfultechnique in cancer treatment, outmatched only by surgery.Up to now about 71000 patients were treated by particletherapy at 32 particle therapy centers (Europe, USA, Japan,

Figure 4: Charge breeding setup with an EBIS-A.

China, South Africa). The trend is increasing.In contrast to other radiation therapies the ion therapy fea-

tures a high biological efficiency causing lethal damagein the tumor cells and leaving the healthy tissue intact(BRAGG interaction).

Compared tocurrentlyused ionsources(primarilyECRionsources) in medical particle therapy facilities EBIS/T sys-tems feature significantly better beam quality (emittance).Furthermore the beam purity, a stringent requirement forpatient irradiation is much higher since plasma ion sourceslike ECR work at operating pressures in the order of 106

mbar (mixing of C, N and O in the plasma) but EBIS/Tusually with 10−8 mbar and better.

In addition, EBIS/T suit the pulse mode operation regimerequired by accelerator facilities such as synchrotrons andcyclotrons since they are normally operating in pulsedmode anyway.

Preliminary proof-of-concept experiments with SiemensMedical have been accomplished. As a next step experi-ments with a Dresden EBIS-SC at the Heidelberg HadronTherapy Facility HIT are scheduled for 2013.

ACKNOWLEDGMENTWork supported by the European Regional Develop-

ment Fund (ERDF) and the Freistaat Sachsen (projectno.100074113 and 100074115) and the German FederalMinistry of Economics and Technology based on a deci-sion of the German Federal Parliament (Central InnovationProgram SEM, project no. KF2558701AB0)

REFERENCES[1] A. Thorn, “Ladungsbruten mit Raumtemperatur - Elektro-

nenstrahlionenquellen” Diss., Dresden, April 2012

[2] A. Thorn et al, “Liquid Metal Alloy Ion Source based metalion injection into a Room-Temperature Electron Beam IonSource” Rev.Sci.Instrum., 83(2):02 A511, February 2012

[3] S. Peggs, PAC07, June 25’07

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