1 / 11

Breakdown energy balance & Preliminary data analysis Jan Kovermann, team meeting 24 .09.2008

Breakdown energy balance & Preliminary data analysis Jan Kovermann, team meeting 24 .09.2008. Overall damage of the surface: Estimations ( O.o.M .): 10cm2 of surface affected by 100um2 breakdown spot size 10kBDs per power test 1/1000 of the surface would be damaged…

reuel
Download Presentation

Breakdown energy balance & Preliminary data analysis Jan Kovermann, team meeting 24 .09.2008

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Breakdown energy balance & Preliminary data analysis Jan Kovermann, teammeeting 24.09.2008

  2. Overall damage of the surface: • Estimations (O.o.M.): • 10cm2 of surface affected by • 100um2 breakdown spot size • 10kBDs per power test • 1/1000 of the surface would be damaged… • But: Total damage looks bigger • Are there any ‘crater’ or other spots where one can locate a breakdown event? • Further SEM observations done(thanks to Samuli!) Before run After run

  3. Damage by ions from Coulomb explosion: • Measured by Magnus&Roger with FC: • ~10E10 ions per event on FC, 1/200 of solid angle  10E13 ions in Coulomb explosion • Ion energies (ToF) ~100eV - 1keV or 2*10-17- 10-16J per ion), secondary electron emissions from FC (bias voltage!) support these values • Estimation: • Radial expansion of the coulomb explosion • 4mm to next iris • 5E11 ions/mm2 on the other side of the iris • ~50uJ/mm2 of energy deposited • In 1ns, this is 10kW/mm2 • Max. 1mJ in total • Seems that the ions cannot heat up the surface to • melting point (pulsed surface heating is 7kW/mm2 • for 68ns, ΔT is only 60K… (by Juoni)) • But: One ion impact each 10x10atoms2, sputtering?

  4. Electrons: • Measured: • High currents (5V in 50Ohms, 100mA) of electrons hit the FC in each BD event, X-rays are produced by these electrons • X-rays pass vacuum window and Al-foils • at least 10keV to be detectable, • for 10E13 electrons (from single • charged ions) dissipated energy is around 20mJ • X-rays pass 14mm Cu and 5mm Fe •  at least 100keV to be detectable • In total: 10E13 electrons with 100keV carry • 160mJ • New experiments: • 1. Precise time measurement • of FC pulse (interferes with power tests…) • 2. Magnetic spectroscopy (1cm bending • Radius in 0.01T field) • 3. Calorimetry of X-rays

  5. Very preliminary analysis of 30GHz structure test data Distribution of missing energy and FC charge HDS4thick (1705BDs) C30 SB (2185BDs)

  6. Very preliminary analysis of 30GHz structure test data Strange pulses… Pre-pulse? Starting time? Incident Transmitted 50% 10% Reflected FC

  7. Very preliminary analysis of 30GHz structure test data Distribution of refl. signal starting times C30 SB (2185BDs) 10% 50% t after inc. pulse start[ns] HDS4thick (1705BDs) 10% 50% t after inc. pulse start[ns]

  8. Very preliminary analysis of 30GHz structure test data Distribution of FC signal starting times 50% 10% C30 SB (2185BDs) t after inc. pulse start[ns] 10% 50% HDS4thick (1705BDs) t after inc. pulse start[ns]

  9. Conclusions • Surface is obviously more damaged than expected by number of BDs • Energy carried by electrons during a breakdown is in the order of magnitude of the missing RF energy • Ions do not seem to play a significant role in the energy balance • Ions can probably change the surface state (smoothing by sputtering??) • Starting time of the BD is not equally distributed during the pulse • There is a ‘pre-reflection’, is it the source of the electrons collected by the FC? • Still some work to do, especially for old test!

More Related