[en] Though Langmuir probes have already proved useful in the field of local plasma diagnostics, the electron cyclotron resonance (ECR) plasma, which is still poorly understood, remained an unexplored one from this point of view. To do the first step, a diagnostics setup (controlled Langmuir probe, bipolar power supply) has been built at the 14.5 GHz ATOMKI-electron cyclotron resonance ion source (ECRIS). Measurements of the cold plasma regions are reported. A modified version of the original methods for characteristics analysis, is also reported. This takes into account the complex nature of the plasma ion component. Depending on the charge state which is optimized for extraction, differences of the calculated electron densities yielded by the two compared theoretical models up to a factor of three were observed which obviously shows the necessary consideration of this effect. The presented work prepares the way for hot plasma region measurements

[en] During the year new heavy ion beams were produced both from gaseous and solids samples (Kr, C, Ni). To ionize from solids we developed a new method to regulate the metal particle flow. This way the generated charge state distribution of the extracted beam could be modified. The investigation of an electron donor electrode (which was built into the ECRIS in 1997) led to a new approach: the injected external electron current will not increase directly the plasma density, but it modifies the trapping and extracting conditions by means of changing the plasma potential. Numerous Kr X-ray spectra have also been measured using a Si(Li) detector at different ion source tunings. Analysing these spectra and the simultaneously measured extracted ion beam intensities the connection between the properties of the internal plasma and the charge state distribution of the external highly charged particle beam has been studied. (K.A.)

[en] Complete text of publication follows. Instrument and beam development. The magnetic mirror ratio of the ECR Ion Source was increased from 1.8 to 2.2 at the injection side. The length of the plasma chamber (and thus, the plasma volume) has been optimized and the vacuum pumping efficiency was increased. Using a simulation software the extraction optics system has been improved. The water cooling system was modified and now it can be operated at any weather conditions. All these developments resulted in an increase of the heavy ion beam currents by a factor of 1.5/10. Figure 1 shows the highest beam currents obtained from the ATOMKI-ECRIS so far. Most extractions were carried out at 10 kV platform potential. Plasma research. Two accompanying papers [1] describe some results on plasma physics research carried out in our lab in 1999. A new project (implantation of N ions into fullerene molecules) will start in 2000. Material research with highly charged heavy ions. At the Frankfurt ECR-RFQ complex. Ar ions with energies of 6/8 MeV and with charge states of 8, 12 and higher were used to irradiate thin (1-2 micrometer) Si crystals. By measuring the transmitted and post-accelerated particles we investigated the modification in average charge state and charge state distribution after passing through the sample. We continued our other collaborations with foreign ECR groups. Promising experiments were carried out in the NIRS institute (Japan) while for the PSI (Switzerland) pionic hydrogen project an ECR Ion Trap was designed. New results are expected in 2000. (author)

[en] Electron Cyclotron Resonance (ECR) plasmas have already been studied in many ways, mainly by x-ray and UV measurements. Langmuir-probes, however, have proven useful for other kind of plasmas, and have rarely been used to explore the ECR plasma. A diagnostics setup has been built at the 14.5 GHz ATOMKI-ECRIS. Results of the cold plasma region measurements are shown. (R.P.)

[en] Results are presented of normal and endohedral fullerene plasmas and beams produced by the 14.5 GHz Electron Cyclotron Resonance (ECR) Ion Source of ATOMKI. A mixed plasma of mainly N, N₂, and C₆₀ was produced in the plasma chamber using a homemade low-temperature oven. Then a beam was extracted from the plasma at U = 700 V extraction voltage. The main goal of the experiment was to produce high intensity of NC₆₀ beams and so high quantity of NC₆₀ bulk material. (R.P.)

[en] Complete text of publication follows. An Electron Cyclotron Resonance (ECR) Ion Source is a tool to generate highly charged ions. The ion beam is extracted from the plasma chamber of the ECRIS. Higher charge states and beam intensities are the main objectives of ECR research. The heart of an ion source is the confined plasma which should be well known to reach those objectives. Information about the plasma can be obtained by plasma diagnostics methods. Langmuir probes were successfully used in case of other plasmas, e.g. TOKAMAK. Until last year plasma diagnostics at the ATOMKI ECRIS was performed by X-ray and visible light measurements. While X-ray measurements give global information, the Langmuir probe method can give information on the local plasma parameters. This is an advantage because the local parameters are not known in detail. By Langmuir probe measurements it is possible to get information on plasma density, plasma potential and partly on the electron temperature. From the experimental point of view a Langmuir probe is very simple. However, the precise positioning of the probe in the plasma chamber (HV platform, strong magnetic field, RF waves) is a difficult task. Also the theory of probes is complicated: the ECR plasma is a special one because the confining magnetic field is inhomogeneous, beside hot electrons it contains cold ions with different charge states and it is heated with high frequency EM waves. What can be measured with a probe is a voltage-current (U-I) characteristics. Figure 1 shows a typical U-I curve measured in our lab. As it can be seen in the figure the diagram has three main parts. An ion saturation current region (I.), an electron saturation current region (III.) and a transition region (II.) between them. These measurements were performed using two different power supplies to bias the probe to positive and negative voltage. To perform more precise U-I measurements we need a special power supply which is presently being built in the ATOMKI. The specialty of this power supply is that we will continuously control the bias voltage of the probe from -500 V tp +500 V with 0.1 V accuracy. Also we can simultaneously measure the electron and ion currents with 0.01 mA accuracy. We designed a new mechanism which will enable us to scan the whole volume of the plasma chamber. One of our plans for the future is to apply this probe to explain the effect of external electron injection into the plasma. (author)

[en] The 14.5 GHz ECR ion source of the ATOMKI is a stand-alone device producing highly charged ion beams for ion-surface experiments and a variety of low charged plasmas and beams for plasma physics studies and for practical applications. In the past two years we performed plasma diagnostics measurements using Langmuir-probes and X-ray camera. Langmuir-probe results allowed estimating the plasma potential close to the resonance zone. The studying of X-ray pictures of Xe-Ar plasmas helps understanding the gas-mixing phenomena. A mixture plasma of fullerene and ferrocene was generated and FeC60 hybrid molecules were detected in the extracted beam

[en] The plasma potential and its distribution play an important role in the highly-charged ion production and it is an important parameter of the electron cyclotron resonance (ECR) plasma. Emitting probes have been successfully used to determine plasma potential distributions in many plasma machines. In the framework of the ATOMKI-ECRIS plasma diagnostics research project, plasma-induced emitting probe was developed. It was proved that in certain conditions such probes could be reliably used without being damaged and without disturbing the plasma. Important observations were made related to the biased-disc effect. In favor of establishing the method of emitting probe usage in ECR plasma, dedicated experiments were performed at the NIRS-Kei2 all permanent compact ECR ion source. Based on the experiences gained after the NIRS experiments, the ATOMKI plasma-induced probe measurements could be interpreted. It was shown that biasing the Disc electrode negatively with respect to the source potential, the plasma potential measured on the resonant zone decreased, while the well-known ion beam current increase was obtained. This result proves the previous assumption [K.E. Stiebing, O. Hohn, S. Runkel, L. Schmidt, H. Schmidt-Boecking, V. Mironov, G. Shirkov, Phys. Rev. ST Accel. Beams 2 (1999) 123501], that the biased-disc changes the plasma potential distribution creating favorable conditions for ion beam extraction

[en] In the last years the ATOMKI-ECRIS group started a local plasma diagnostics research project, to adapt the probe to the ECR plasma conditions. Until now we made progress in the study of the cold plasma region. The results has been reported in e.g. [L. Kenez, S. Biri, J. Karacsony, A. Valek, Nucl. Instrum. Methods Phys. Res. B 187 (2) (2002) 249; L. Kenez, S. Biri, J. Karacsony, A. Valek, T. Nakagawa, K.E. Stiebing, V. Mironov, Rev. Sci. Instrum. 73 (2) (2002) 617]. In this Letter we make a step further report the first experiments carried out in the hot ECR plasma. We used a simple probe inserted in the hot resonant plasma. We point out that this probe works as emitting probe. We developed a theoretical model to explain the unusual shaped voltage-current characteristics and tested its validity using computational study of the presented theory