Mironov, V

Strekalovsky, O V

Tokareva, N

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EXPERIMENTAL STAND TO STUDY EXPLORATION OF THEAFTERGLOW OF THE PULSED ELECTRON CYCLOTRON RESONANCESOURCE UNDER THE INJECTION OF NEUTRAL FLUXESV. Mironov, O. Strekalovsky, N. Tokareva, JINR, Dubna, RussiaAbstractAn experimental stand to study the free expansion of alaser ablation plasma under the injection of neutral fluxesis described. The Q-switched YAG:Nd+3 laser is focusedonto the surface of a Zn target. The plasma pulse durationis 10 µs, the ionization degree in the flux is about 5%, thevelocity of neutrals is in the range of 106 cm/s. The controland measurement system is based on the CAMACstandard, an IBM PC computer and a digital oscilloscope.The control solution has been created with the LabVIEWgraphical language and “WaveStar” Software forTektronix oscilloscope.1 THE EXPERIMENTAL STANDAn experimental test facility[1] to investigate injectionof the laser ablation plasma into the open magnetic bottletraps simulating the ECRIS magnetic field configurationhas been developed at PPL JINR. The schematic of theexperiment is shown on Fig. 1.Figure 1: The experimental setup scheme.The laser beam of YAG:Nd+3 Q-switched laser wasfocused by a lens onto a 0.5 mm spot on the Zn targetmounted in a vacuum chamber to produce the laserablation plasma. The plasma fluxes are collimated by adrift tube and then crossed at 5.5 cm from the target by alaser produced ion Zn+ beam (5-25 keV, 0.4 mA, 20 •s). Asmall fraction of ions is neutralized due to resonantcharge-exchange processes in Zn+ + Zn0 collisions, leavesthe plasma, and enters into a time-of-flight massspectrometer. These neutrals are fast enough to beefficiently detected by a secondary emission multiplier(SEM). An electrostatic deflector (ESD) was mounted toremove the charged particles from the flux before theSEM. The charged components of the plasma wereinvestigated using a stainless steel 0.2 mm diametercylindrical probe placed close to the drift tube. A digitaloscilloscope was used to record the SEM and probeoutputs. A fast photomultiplier tube (PMT) was used todetect visible radiation emitted by the plasma and Zn+beam.A delay between the ion beam and the laser ablationplasma production was adjusted to have sufficient timeintersection of the fluxes.2   THE CONTROL ELECTRONICS2.1  The control electronics of the experimentalstand.The concrete experimental setup was constructed fromstandard CAMAC modules ( amplifiers, ADC, TDC,counters … ) and a program for multiparameter analysis“VEDA”. Gamma-spectrometer, X-ray spectrometer andother measurement schemes can be realized in this setup.To set different time intervals between the two laser shots,a new electronic module based on a Phillips 80552Figure 2: The electronics scheme.microcontroller was created. The control program for thismodule is loaded by a serial interface RS232 from aInternational Conference on Accelerator and Large Experimental Physics Control Systems404International Conference  Accel rator and L rge Experim ntal Physics Control Systems, 1999, Trieste, Italypersonal computer and may be easily modified for aspecific experiment.The second task of this module is to produce timeintervals for X-ray spectra accumulations. We try to findsome phenomena in the plasma by analyzing the growthof the spectra at fixed time intervals from 2-5 ms.2.2 Software for digital oscilloscope TDS380.Digital oscilloscope TDS380[3] is used for signalregistrations. “WaveStar” software from Tektronics isvery attractive to handle the scope manually, but it isimpossible to start a new cycle of measurementautomatically. One oscillogram is generated for each shotof the lasers. At the next measurement step a new timeinterval will be set and a new oscillogram will beproduced. Cycles repeat until the end of interestingdiapason.   The TDS380 communicates with the personalcomputer by sending commands and queries by GPIB orRS232. Commands [4] modify oscilloscope settings or tellthe oscilloscope to perform specific actions; queries causethe oscilloscope to return data and information about itsstatus.We needed faster development, so we used LabView(National Instruments) with its graphical programming,integrated libraries and flexibility for easy modification.3  CONCLUSIONSWith a Tektronix TDS380 digital real-time oscilloscopeas a very attractive tool for displaying and measuringwaveforms, a multichannel analyzer in CAMAC and apowerful graphical development language (LabView) wewere able to create high performance solutions for our teststand to study the free expansion of laser ablationplasmas.REFERENCES[1] V. Mironov, G. Shirkov , O. Strekalovsky, N.Tokareva “Exploration of the afterglow of the pulsedelectron cyclotron resonance source under theinjection of neutral fluxes ”, ICIS ’97, Taormina,September 1997.[2] 80C51-Based *-bit Microcontrollers. Data Handbook.Philips Semiconductors IC20, 1993.[3]  Tektronix TDS380 Digital Real-Time OscilloscopeUser Manual. Tektronix, Inc. 1995.[4] TDS340A, TDS360 & TDS380 Digital Real-TimeOscilloscopes Programmer Manual. Tektronix, Inc.1995.405

Experimental Stand to Study Exploration of the Afterglow of the Pulsed Electron Cyclotron Resonance Source under the Injection of Neutral Fluxes

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