Gyrotron Multi-Charged Ion Source
Creation of Prototype of Multi-Charged Ion Source Based on ECR Discharge Sustained by Powerful Gyrotron Radiation with High-Current Beam and Pulse Frequency Repetition up to 1 Hz
Tech Area / Field
- PHY-PLS/Plasma Physics/Physics
8 Project completed
Senior Project Manager
Safronova O N
Russian Academy of Sciences / Institute of Applied Physics, Russia, N. Novgorod reg., N. Novgorod
- CNRS / IN2P3 / Institut des Sciences Nucléaire, France, Grenoble
Project summaryThe aim of present Project is the development of a prototype of pulsed ECR source of multicharged ions (MCI) with high ion current (up to 100 emA) and high repetition rate (up to 1 Hz). Pulsed sources of MCI beams are widely used in science and technology at present, nevertheless to solve a row of modern problems it is necessary to increase significantly current of MCI beams. For example for the future accelerator of heavy ions in CERN the beams of lead ions with charge 27, current up to some emA and duration 100 ms with repetition rate 1 Hz are required. This is not achievable with use of traditional ECR sources of MCI.
A significant growth of ion beam current can be obtained by use of powerful short-wave radiation of gyrotrons in ECR sources. Using gyrotron radiation in experiments at IAP RAS executed in frame of ISTC project 1496 allows to increase significantly plasma density in the discharge (up to 1013 cm-3 that is about an order magnitude higher than in traditional ECR sources) while electron temperature remains at the optimal level for MCI formation, thus giving an opportunity to obtain higher MCI current. This way of investigations started after a series of experimental researches under the leadership of Professor R. Geller, noticeable gain in the current of extracted MCI beams was obtained due to change in radiation frequency from 10 to 18 GHz. Based on these results a semi-empirical scaling was proposed according to which the extracted MCI current is increased proportionally to the RF frequency squared while MCI distribution is slightly shifted in the direction of higher charge state.
Our recent investigations of pulsed ECR discharge in the pulsed direct magnetic trap (with 37.5 GHz gyrotron with 100 kW power and 1 ms pulse duration) carried out in IAP RAS have demonstrated the possibility to reach high plasma density (up to 1013 - 1014 sm-3) and obtain record densities of ion flow (up to 1 A/cm2). These experiments confirm the perspectives of new generation of MCI sources pumped by millimeter gyrotron radiation. A plasma containing highly charged ions was created. However the quality of the ion beam extracted from the plasma was low due to insufficient voltage on the extractor and the low quality of the of ion channel. Moreover the laboratory setup had operating repetition rate 0,01 Hz insufficient for use in applications. The main goal of the suggested project is the formation of high current density ion beam of multicharged ions that will be suitable for applications.
The main units of the prototype will be: the superconducting magnetic trap, the pulsed 37.5 GHz gyrotron with power supplies (100 kW power, pulse duration up to 5 ms, pulse repetition rate up to 1 Hz), the high-voltage pulsed extractor with voltage up to 100 kV, the system of ion analysis, the electrodynamic system of microwave launch into the plasma, and the system of pulsed gas injection.
In the frame of the Project it is planned to determine optimal conditions of ion generation, methods of high current density ion beam formation, to determine technological features of source operation with high pulse repetition rate, to perform the experiments to clarify other possible further applications (e.g. surface processing by multicharged ions).
In short: ISTC project #1496 (1999 – 2002) allowed to evidence the exceptional ECR plasma properties obtained with 37,5 GHz gyrotron. The new project proposal is aimed to obtain not only the ECR plasma but also then realization of a reliable ion beam extracted from this plasma – this is the logical step of this effort, which should lead to an actual breakthrough.
The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.
ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.