Andrä, J. H.

Paper	Title	Page
MOCO-B02	Continuous and Pulsed Operation of a Highly Efficient 18 GHz Plateau-ECRIS	13
	J. H. Andrä Westfaelische Wilhelms-Universität Muenster, Muenster B. Albers, A. Heinen, L. Hupe, M. Kahnt, L. Nowack, H. W. Ortjohann, A. Taschner, Ch. Vitt, S. Wolosin Institut fur Kernphysik, Westfalische Wilhelms-Universitat Munster, Munster
	A highly efficient 18 GHz Plateau-ECRIS (PECRIS V) has been developed. The magnetic field on axis has a flat plateau-minimum. Together with a very strong permanent magnetic hexapole it creates a large resonance volume. In this resonance volume electrons are electron-cyclotron-resonance-heated more efficiently than in standard ECRIS and the maximum density of the plasma is obtained near the axis from where ions are primarily extracted. The plasma chamber is designed as a microwave resonator with specific end-plates to achieve high microwave amplitudes on the axis in spite of the low microwave power of <500 W. Up to 4 microwave frequencies have simultaneously been used. By the use of several frequencies at, above , and below the plateau, we become less sensitive on density variations in the plasma. We also present a technique for the extraction of intense short pulses of highly charged ions. This technique temporarily reduces the magnetic field on the extraction side and is an interesting alternative to the afterglow, in particular for the highest charge states. The design and the highly efficient operation of PECRIS V may thus serve as guideline for the future conceptions of ECRIS.
	Slides
TUCO-C01	Three-Dimensional Simulation of Electrons and Ions in ECRIS	154
	J. H. Andrä Westfaelische Wilhelms-Universität Muenster, Muenster
	Electron-Cyclotron-Resonance-(ECR)-Heating (ECRH) is known to produce non-equilibrium plasmas with the total non-Maxwellian energy in the electrons while the ions stay below 1 eV. Theories based on Maxwell distributions are thus unable to correctly describe ECR-Ion Sources (ECRIS). Particle In Cell (PIC)-techniques are feasible only with significant approximations in the extremely complicated magnetic structure of an ECRIS. This is the reason to concentrate all efforts on the calculation of various electron distributions in an ECRIS taking into account all three-dimensional static fields, dynamic microwave fields, and all collisions of the electrons. To this end the Boris-algorithm is introduced which is shown to be very efficient and precise for all conditions in an ECRIS including the resonance transitions. The electron distributions clearly show the low efficiency of ECRH in a standard ECRIS with a central minimum of the axial magnetic field compared to the high ECRH-efficiency in a plateau-ECRIS with a flat central minimum. A non-relativistic version of the code is used to demonstrate the positive effects of ion-CRH on the confinement of the ions with far reaching consequences.
	Slides
TUCO-D02	Ion Cyclotron Resonance Heating in a Plateau-ECRIS	168
	M. Kahnt, B. Albers, L. Hupe, L. Nowack, H. W. Ortjohann Institut fur Kernphysik, Westfalische Wilhelms-Universitat Munster, Munster J. H. Andrä Westfaelische Wilhelms-Universität Muenster, Muenster
	It is shown why static or low frequency electric fields perpendicular to the magnetic field can penetrate into a magnetized plasma of high density. A configuration of electrodes is chosen for the application of radio-frequency electric fields to heat by ion-cyclotron-resonance (ICR) Ar(q+)-, H-, and He-ions in PECRIS V with a magnetic plateau and a great resonance volume. It is shown that all ions ICR-heated in this resonance volume gain rotational energy E(rot) and stay thus better confined leading to a drop so that their extracted currents. E(rot) of these ions thermalizes while they are further ionized by electron collisions so that the extracted currents of Ar((q+n)+)-ions do show a considerable increase with 2<n<7. The extracted currents of the two ICR-heated light ions do show only drops which will be discussed in detail. As proof of their gain of E(rot) the energy gain of extracted He-ions has been measured. The ICR-heating of multi-charged ions may thus be a technique to considerably improve the currents of the highest charge states.
	Slides