Beusch, A.

Hubert, C.

Kupka, K.

Lommel, B.

Severin, D.

Tomut, M.

Trautmann, C.

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GSITemplate2007 Beam Monitoring on Graphite Targets by Infrared Thermography  M. Tomut1,2,#, C. Hubert1,3, K. Kupka1,3, B. Lommel1, A. Beusch1,D. Severin1,C. Trautmann1,3 1GSI, Darmstadt, Germany; 2 NIMP, Bucharest, Romania;  3Technische Universität Darmstadt, GermanyThe thermal print of an ion beam on a target is related to the power density deposited in the target [1]. Infrared (IR) radiometry is one of the few methods suitable for the monitoring of high-intensity primary beams on produc-tion targets at FAIR. This work summarizes first results on online infrared imaging of beamspot size on thin graphite targets in experiments with ion beams at MeV-GeV energies using a FLIR SC 7500 high sensitivity, cooled IR camera. Due to their good thermo-mechanical properties and high emissivity, graphite targets are ideal for thermography-based beam diagnostic.   Figure 1: Temporal evolution of temperature within the center of the beam spot during irradiation with 1x109 i/cm2s  197Au ions with a energy of 3.6 MeV/u, 4 ms pulse length and a repetition rate of  38 Hz.   Figure 2: Sequence of infrared images of beam spot on thin graphite targets with increasing beam flux. Each im-age corresponds to maximum intensity during a pulse, for a 3.6 MeV/u, 4 ms, 38 Hz 197Au beam.     01002003004009.0E+07 1.0E+10 2.0E+10 3.0E+10 4.0E+10Flux (i/cm2s)Temperature (oC) Figure 3: Maximum temperature recorded within the beamspot on thin graphite targets exposed to 3.6 MeV/u 197Au ions, with increasing beam intensity, as a function of beam flux. Figure 1 presents the time evolution of the temperature maximum within the beamspot of 3.6 MeV/u Au ions. The high sensitivity and low integration time of the cam-era provide a high accuracy monitoring of intensity varia-tion during individual pulses. This type of information was used as input in finite element calculations of beam-induced thermal stress in targets. About 2 s are necessary for the temperature in the target to reach the steady state at the beginning of the irradiation, for the given beam parameters. Upon the beam stop, the time constant of the temperature decay in the target can be related to the ther-mal conductivity of the target materials. To get accurate temperature distribution from the radi-ometric image of the ion heated target, previous calibra-tion of the emissivity of the target and environment and of the transmittance of the beamline IR viewport are neces-sary. Figure 2 shows a series of thermal prints of Au ion beam pulses with increasing intensity on graphite targets. Snapshots are taken after the temperature in the targets reached a steady state condition (> 2 s) and at the maxi-mum pulse intensity. The increase of the maximum tem-perature in the beamspot with increasing ion flux is shown in Figure 3. A detailed analysis of the fully radio-metric image will be used for inferring the beam power density profiles providing the beam intensity profile. To validate these results, cross-checks using luminescence targets will also be done. This beam diagnostic technique is particularly suited for high intensity cases where other techniques would fail. Thermographic screens made out of carbon materials are also a cheaper alternative to lumi-nescence screens.  [1] H. Buttig, “Beam Diagnostic by Infrared Thermogra-phy” ZKF-453 Report Forschungszentrum Rossen-dorf, Aug. 1981.  #m.tomut@gsi.de GSI SCIENTIFIC REPORT 2012 PNI-INHOUSE-EXP-38407

Beam Monitoring on Graphite Targets by Infrared Thermography

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Beam Monitoring on Graphite Targets by Infrared Thermography

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