Progress of SAFERIB and EURISOL-DS (WP5) at LMU P.G. Thirolf, LMU München (W. Carli, M. Gross, A. Kohlhund, F. Nebel, J. Neumayr, R. Stoepler, J. Szerypo)
Project tasks of LMU: - SAFERIB:
Characterization of a hot, open fission source selection of materials test of thermal properties (metals, insulators, feedthroughs) -> prototype tests: heating, emittance
- EURISOL-DS (WP5): Study of containment of volatile radioactivity cryotrap design and characterization -> prototype tests: localization capabilities
Purification system for vacuum exhaust gases -> first filter prototype tests
Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Fission Target Ion Source Inventory: ca. 1g 235U in graphite matrix ca. 1014 fissions/sec. Operational conditions: - 2400oC (3.2 kW nucl. heating) - 30 kV
Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Fission Source Prototype Ti carrier
Mo, W heat shields
BeO insulator Re-container
electrical contacts
separation of source and carrier
Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Tests of Source Protopyype: Material & Design Properties
material and design properties under huge heat load: - thermal expansion vs. alignment precision - temperature dependence of insulator performance (C sublimation of graphite matrix) - functionality of electrical contacts beam emittance lifetime of W-filament
Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Source Test Bench at MLL
Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Emittance meter coupled to test bench
Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Stable Beam Extraction Tests graphite matrix in Re-cylinder loaded with Nd extraction via surface ionization Nd mass spectrum behind analyzing magnet: 142 144
146 143 145 148 150 133Cs
intensities according to isotopic abundances Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Nd Beam Emittance
y Integral: 10,5π mm mrad
y Integral: 10,5π mm mrad @ 21 keV 0
2,00E-012
10
1,80E-012 0
2,5E-13 5E-13
1,60E-012
7,5E-13
2,5E-13
1,40E-012
5E-13
1E-12
5
1,20E-012
7,5E-13
1,25E-12 1,5E-12
I [A]
8,00E-013
1,25E-12
6,00E-013
1,5E-12 1,75E-12
4,00E-013 2,00E-013 0,00E+000
2E-12
10 15
5
b
0
b [mrad]
1,00E-012
1E-12
1,75E-12
0
2E-12
-5
10
[m d] ra
-5
5 -10 0
mm y[
]
-10 0
5
10
15
y [mm]
experiment: 10.5 π mm mrad (@ 21 keV) simulation: ~12 π mm mrad (@ 30 keV) Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Source Heating temperature control via pyrometer: -
external heating of source: 45 A 350W (350V/1A cyl./shield) temperature reached: 1800 K extraction voltage: 21 kV
mechanical displacement of extraction channel during heating
Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Thermal Distortions Diagnostics after dismounting: - separation of source/carrier mechanical force needed - removal of heat shield block (bayonet socket) -> internal stress released during heating distortions (?) - Re cylinder support rod tilted - W filament not affected
}
Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Ceramic Insulators carbon sublimation onto ceramic insulator surfaces - operated for ~20 hours at ~1800 K:
Resistance of BeO insulators: Re cylinder/filament Re cylinder/outside mass filament/outside mass
~1800oC/20 hrs 60 kΩ 150 kΩ 114 kΩ
~2000oC/7 hrs 25.7 kΩ 8.3 kΩ 7.5 kΩ
further tests: quantification of carbon sublimation rate design modification: ‘sealed’ coverage of insulator surfaces Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Tests of Cryotrap Prototype Testbench facility at MLL: cryotrap coupled to lHe refrigerator ~ 600 W cooling power at 12 K
cryotrap prototype equipped Channel 3 with 6 thermal sensors (Si diodes):
Channel 5
He Return
Channel 4 Channel 6 He Supply
length: 1m Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Cryotrap Testbench pressure sensor: PLeak
test leak
turbo pump
pressure sensor: PM
pressure sensor: Ppenning
cryopanel He In/Out
mass spectrometer
He supply lines
Peter Thirolf, JRA-10 SAFERIB
pressure sensor: PR
mass spectr. turbo pump
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Pressure Measurements 4 sensors compared in 3 sequential measurements: introduce calibrated test leakage (dry N2) reproducibility of pressure values PLeck 1 PHiden 1 PCryo 1 PPenning 1 PLeck 2 PHiden 2 PCryo 2 PPenning 2 PLeck 3 PHiden 3 PCryo 3 PPenning 3
1E-3
Pressure [hPa]
1E-4
1E-5
1E-6
1E-7
1E-8 1E-6
{ { {
cryopumping 1E-5
1E-4
1E-3
0,01
0,1
1
Leak [hPa l/s]
Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Comparison: 2 cryotrap designs ‘small‘ panel (SP): - only for test purposes - 2 shielding paddles
‘large‘ panel (GP):
- turbulent regions of gas flow with compression/expansion temperature distribution
- unambiguous gas flow characteristics - simple mechanical design, no weldings
Surface ratio: A(GP)/A(SP) ~ 18 (without shield) Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Localization capability of Cryo Trap N2 test leaks
20 K efficient N2 pumping: 20K: increased pumping capacity for Krypton (-> vapor pressure) Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Shielding of external thermal load 1
4. 3.
10 layers of ‘superinsulation‘ foil SP N 8K GP N 23K GP N 32K VL18K GP N 25K VL 8K GP N 31K Isoliert GP N 24K Isoliert
0,1
Carry over pR/pM
2.
t
0,01
1. 1E-3
1E-4
1E-5
1E-6 1E-6
1E-5
1E-4
1E-3
0,01
0,1
1
10
100
Leak [hPa l/s]
continuous degradation of performance of Large Panel dominant pumping contribution from cold He supply line for larger T thermal isolation blocks conductance to supply line and blocks pumping Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Radial Temperature Distribution - large leakages cause icing of the cryopanel with ice layer: 23.9 K
without ice layer:
23.9 K
48.5 K
53.8 K
?
? 9.0 K
17.5 K
19.6 K
21.4 K
37.9 K
36.4 K
54.9 K
48.5 K
- iced panel (lower emissivity): lower temperatures better shielding of external thermal load - temperature distribution cannot be explained by gas flow pattern indicates internal leak in Large Panel experimentally confirmed: > 1l/min Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Present Conclusions from Cryo-Trap Tests design value of 20 K for cryotrap operation (from vapour pressures) could be confirmed; operation below 20 K not needed better localization of gases by larger panel surface present cryotrap design reveals temperature-related mechanical problems: - inconsistent temperature distribution indicated internal leakage between He-In and He-Out channels - most likely internal welding seam developed leak under thermal stress internal leak prevented cool-down below 20 K in regular operation only with shielding by ice layer from massive test leakage nominal operational temperature could be reached influence of external thermal load could not be shielded by passive multilayer super-insulation revise design of cryotrap test active shielding via cooling of thermal shield in contact with He supply line. Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Vacuum exhaust aerosol filtering: Design of Test System
QMS Small volumes ~ 1l ∆p ~ mbar
Large volume 3 ~ 10 l -4 ~ 10 mbar
Filter (Particle counter) Flow Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Metal In-Line Gas Filter cleanest, most efficient all-metal filter available sintered nickel membrane filter specification: particle retention: > 99.9999999% < 0.03 particles/liter larger than 0.01µ µm
tests have just started aerosol generator needs to be implemented Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
Alternative Filter Concepts
• design decay tanks as gravitational traps: - baffle on bottom of tank - aerosols fall through, cannot be released any more • use zeolith as molecular sieve: - fill decay tank with zeolith - particles >0.5 nm will be trapped by collisions • use commercial metal filter with confirmed retainment factor of 109 and pore size of 3 nm
Peter Thirolf, JRA-10 SAFERIB
2nd EURISOL-DS (T5)/SAFERIB Annual Meeting, Munich, October 12./13., 2006
