Systematic studies on pellet beam production M.Büscher, A.Gerasimov, V.Chernetsky, P.Fedorets, A.Dolgolenko,V.Balanutsa, A.Boukharov, L.Gusev, S. Mineev, S.Podchasky, D.Spölgen, I.Tarasenko (Activities in Juelich and in Moscow over in frame of FP7 project)

FP7 tasks for the pellet target: production of nozzles with diameters down to 5 μm pellet production with minimum diameters high frequencies above 100 kHz of the target operation measurement of the pellet-beam properties

Unexpected problem with droplet production (first half 2012) H2H2 N 2, f=261 kHz No operation point for hydrogen in frequency scale. Very clean monodisperse decay for nitrogen at several frequencies. Conclusion: additional investigation are needed. The same nozzle Ø=57 μm Test of new piezo elements with H 2 and N 2 Temperature sensor

New construction of the generator More save fixing of piezo-rings inside the body of the generator. The transfer of the vibrations from piezo-rings to the nozzle should be much less depend from low temperature distortion of the material of the generator. Old generator (type N1) in assembling with the condenser New generator (type N2): 3 bodies and one assembling with piezo-rings June 2012

Result of the test with new generator with H 2 nozzle Ø=42 μm f=46.3 kHz Monodisperse droplet production with the new generator for hydrogen June 2012, new generator

Nozzles with diameters down to 5 μm Technology of the nozzle production had been developed in both FZJ and ITEP Nozzles with diameter less then 10 µm are possible to produce. Photos of internal channel of the nozzle Ø=30 μm Ø=11 μm Ø= 5 μm nozzle edge But the main problem is the nozzle blocking during operation! Support: EU FP7 – Future Jet

Pellet production with frequencies above 100 kHz with small nozzles 2010, H 2 jet diameter ≤ 10 μm, f=181 kHz production nozzles with diameters down to 5 μm is possible pellet production with high frequency is possible problem of blocking the nozzle short live time of the small nozzles (only one cooling cycle) Conclusion: in parallel to the studies with small nozzles we start the investigation of the small diameter droplet production with help of auxiliary blowing gas

H 2 nozzle Ø =42  m f=46.3 kHz First test with nozzle blowing in June 2012 But! In the beginning it was idea of blowing the outlet of the nozzle to warm up it. Results: 1)frozen droplets were observed in triple point chamber with He blowing gas 2) in this experiment the diameter of droplets was significantly less as for Rayleigh decay Conclusion: continue investigations, change the construction of the blowing, make it symmetric and in parallel test the idea of decreasing the jet diameter

Idea of the nozzle blowing With help of the focussing gas flow reduce the jet diameter Advantage: possibility to use bigger nozzle diameters with less probability of blocking Goal: production of droplets with diameters < 10 μm A. M. Gañán-Calvo, PRE 79, (2009) V.Varentsov, NIM A 646, 12 (2011)

Test with nozzle blowing in December 2012 blowing gas entrance piezo elements nozzle

First result with nozzle blowing in December 2012 without auxiliary gas (no blowing) f = 82 kHz f = 122 kHz. H 2 droplets, nozzle diameter: 35 µm Usual monodisperse droplet production at resonance frequencies

First result with nozzle blowing in December 2012 H 2 droplets, nozzle diameter: 35 µm auxiliary gas He auxiliary gas H 2 with auxiliary gas He jet starts to freeze on the sluice inlet with auxiliary gas H 2 jet does not freeze Plans: 1)tuning of auxiliary gas flow by MKS flow controller 2)change geometry of blowing according to literature for room temperature predicted by A. M. Gañán-Calvo, PRE 79, (2009)

Overview of developing nozzle blowing method Generator type N3, December 2012 Generator type N4, April 2013 Generator type N4: Geometry of blowing as recommended in: blowing gas nozzle generator Generator type N2, June 2012 A. M. Gañán-Calvo, PRE 79, (2009)

Development of the nozzle blowing method Generator type N4, April 2013 Generator type N3, December 2012 fixed blowing ring around the nozzle calibrated orifice Ø 0.5 mm Generator type N2, June 2012Old generator (type N1) blowing gas entrance Support: EU FP7 – Future Jet

New gas supply scheme for auxiliary gas April 2013 RVC200 pressure control H 2 main nozzle H 2 auxiliary nozzle blowing H 2 auxiliary MKS flow control H 2 or He New scheme of auxiliary gas system RVC200 pressure control H 2 main nozzle H 2 auxiliary nozzle blowing H 2 auxiliary H 2 or He Old scheme of auxiliary gas system

Prepared observation points for the line scan cameras Triple point chamber Outlet from sluice Inlet of skimmer Outlet from cryostat - camera N2 camera N1 Scattering chamber – camera N2

Noise measurements GainNoise amplitude Camera N1 Noise amplitude Camera N2 -33 (min) (max) % of pixels are in the range for noise amplitudes. Noise comes from electronics and depends only on gain. For the closed lens results are the same. Noise does not depend on exposure.

More exposure – broader cluster center distribution. Clusters from different droplets start to join. More gain – more noise and signal amplitude come to saturation (255). Low gain – very low detection efficiency. Optimal for measurements in the triple point chamber are exposure µs and gain (-20). Triple point chamber (parameters) Exposure, μs GainNoise cut ≥ Cluster center σ Density σ

Triple point chamber (examples) gain -20, exp. 0.1 μs Cluster center Each pixel density Clusters per line Density spectrum is more representative as centers of clusters. Cluster center Each pixel density Clusters per line cut off noise with amplitude 1 Typical spectrum for clean selection

Inlet of skimmer, Ø=2 mm Outlet from sluice Ø=420 μm, L= 144 mm Observation with the video cameras + laser Not perfect adjustment follow to scattered profile on the outlet of sluice. Conclusion: hardware and software are ready for measurement of the beam profile

Test of adjustment system in Moscow Alcohol will be pressed through the nozzle by nitrogen gas Jet will be observed by 2 CCD cameras in the real installation inside the target adjustment system in assembling in Moscow triple point chamber alcohol nitrogen Support: EU FP7 – Future Jet

Preparation of the test place in Moscow Test hall, April 2013 Test hall, 2012 Full renovation of the test hall, November April 2013

Plans for the second period of FP7 project 1)Continue investigation of cleaning/protection procedures for nozzles (especially for small diameters) 2)Further study the method of “blowing” the nozzle for decreasing the jet/pellet diameter 3)Measurement of the pellet-beam properties