Current status of a cryostat for the provision of hydrogen ... · Current status of a cryostat for...
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Current status of a cryostat for the provision of hydrogen with adjustable ortho-para-ratio for neutron moderation S Eisenhut 1 , M Klaus 1 , C Haberstroh 1 , J Baggemann 2 , T Cronert 2 , Y Beßler 3 , C Lange 1 1 Technische Universität Dresden, Dresden, Germany 2 JCNS, Forschungszentrum Jülich, Jülich, Germany 3 ZEA-1, Forschungszentrum Jülich, Jülich, Germany Motivation The Problem Cryogenic moderators using para-H 2 are currently widely used to produce cold neutrons. However, the neutrons cannot reach full thermalization, i.e. the neutron temperature lies above the temperature of the moderating medium. This is caused by the extremely low scattering cross section of para-H 2 for neutron energies below 30 meV. The Idea Adding a well-defined amount of ortho-H 2 can in- crease the scattering cross section of the liquid hydrogen mod- erator and help moving the neutron spectrum towards lower energies, and hence reducing the neutron temperature. The Vision Building a cold moderator of unprecedented perfor- mance for the High Brilliance Neutron Source (HBS) currently being developed by Forschungszentrum Jülich in Germany LH 2 moderator prototype [C1Po2A] Concentration monitoring Method Based on speed of sound (SRS BGA244) Accuracy Currently being assessed and improved Current status Commissioning of mixing cryostat successful Full conversion in ortho-para-H 2 catalyst shown Mixing operation for several ortho-para-H 2 ratios and concentration monitoring demonstrated Commissioning with moderator vessel to be done Summary A small-scale hydrogen liquefier with an adjustable ortho-para- H 2 ratio has been built and commissioned. As soon as a safe operation with the moderator vessel has been demonstrated, the system is ready for operation at a neutron source, e.g. the training reactor AKR-2 at TU Dresden, for measurements of neutron spectra resulting from different hydrogen composi- tions. This will be a crucial step towards the development of highly optimized cryogenic hydrogen moderators for use in Compact Accelerator-Driven Neutron Sources, such as the fu- ture High Brilliance Neutron Source in Jülich, Germany. System design Mixing cryostat Moderator extension LH 2 200 ml 5 cm 10 cm HX He-H 2 Triple tube-in-tube type for separate condensation of para-H 2 and normal-H 2 He-cooled radiation shield LH 2 volume 200 ml He heater Stabilizes the He temperature above H 2 freezing temperature Moderator vessel With He cooling channels Thermal neutrons Speed of sound measurement device SRS BGA244 Current set-up 310K a o-H2 – a p-H2 = 11 m/s Future set-up 233K a o-H2 – a p-H2 = 35 m/s 8 meV T neutron = 90K He in He out LH 2 in LH 2 out He cooling channels Contact information Technische Universität Dresden Intitute of Power Engineering Bitzer-Chair of Refrigeration, Cryogenics and Compressor Technology 01062 Dresden, Germany Sebastian Eisenhut E-Mail: [email protected] Phone: 0049 351 463 39736 Mixing cryostat Moderator extension para ortho Moderator vessel HX He-H2 with catalyst MFCs H 2 Concentration Measurement Ventline H 2 mix 25 100% p-H 2 25% p-H 2 100% p-H 2 LHe El. Heater Rad. shield He recovery
Transcript of Current status of a cryostat for the provision of hydrogen ... · Current status of a cryostat for...
Current status of a cryostat for the provision of hydrogen with adjustable
ortho-para-ratio for neutron moderation S Eisenhut1, M Klaus1, C Haberstroh1, J Baggemann2, T Cronert2, Y Beßler3, C Lange1
1Technische Universität Dresden, Dresden, Germany 2JCNS, Forschungszentrum Jülich, Jülich, Germany 3ZEA-1, Forschungszentrum Jülich, Jülich, Germany
Motivation
The Problem Cryogenic moderators using para-H2 are currently
widely used to produce cold neutrons. However, the neutrons
cannot reach full thermalization, i.e. the neutron temperature
lies above the temperature of the moderating medium. This is
caused by the extremely low scattering cross section of para-H2
for neutron energies below 30 meV.
The Idea Adding a well-defined amount of ortho-H2 can in-
crease the scattering cross section of the liquid hydrogen mod-
erator and help moving the neutron spectrum towards lower
energies, and hence reducing the neutron temperature.
The Vision Building a cold moderator of unprecedented perfor-
mance for the High Brilliance Neutron Source (HBS) currently
being developed by Forschungszentrum Jülich in Germany
LH2 moderator prototype
[C1Po2A]
Concentration monitoring Method Based on speed of sound (SRS BGA244)
Accuracy Currently being assessed and improved
Current status
Commissioning of mixing cryostat successful
Full conversion in ortho-para-H2 catalyst shown
Mixing operation for several ortho-para-H2 ratios
and concentration monitoring demonstrated
Commissioning with moderator vessel to be done
Summary A small-scale hydrogen liquefier with an adjustable ortho-para-
H2 ratio has been built and commissioned. As soon as a safe
operation with the moderator vessel has been demonstrated,
the system is ready for operation at a neutron source, e.g. the
training reactor AKR-2 at TU Dresden, for measurements of
neutron spectra resulting from different hydrogen composi-
tions. This will be a crucial step towards the development of
highly optimized cryogenic hydrogen moderators for use in
Compact Accelerator-Driven Neutron Sources, such as the fu-
ture High Brilliance Neutron Source in Jülich, Germany.
System design
Mix
ing
cry
ost
at
Mo
de
rato
r e
xte
nsi
on
LH2
200 ml
5 cm
10
cm
HX He-H2
Triple tube-in-tube type for
separate condensation of
para-H2 and normal-H2
He-cooled
radiation shield LH2 volume
200 ml
He heater
Stabilizes the He
temperature
above H2 freezing
temperature
Moderator vessel
With He cooling
channels
Thermal
neutrons
Speed of sound
measurement device
SRS BGA244
Current set-up 310K
ao-H2 – ap-H2 = 11 m/s
Future set-up 233K
ao-H2 – ap-H2 = 35 m/s
8 meV
Tneutron = 90K
He in He out
LH2 in LH2 out
He cooling
channels
Contact information
Technische Universität Dresden
Intitute of Power Engineering
Bitzer-Chair of Refrigeration, Cryogenics and Compressor
Technology
01062 Dresden, Germany
Sebastian Eisenhut E-Mail: [email protected]
Phone: 0049 351 463 39736
Mixing cryostatModerator extension
para ortho
Moderator vessel
HX He-H2 with catalyst MFCs
H2
Concentration Measurement
Ventline
H2 mix 25 100% p-H2
25% p-H2
100% p-H2
LHe
El. Heater
Rad. shield He recovery
