Find out a little more about the Cryogenic's products available through TalaveraScience!
Cryogenic Ltd manufactures cryogenic equipment, measurement systems, cryostats and superconducting magnets including cryogen free systems for magnetic resonance applications.
TalaveraScience is the senior sales consultancy for Cryogenic Ltd.
Cryogenic Ltd has been a pioneer of cryogen free superconducting magnets and cryostats for a variety of applications for more than 20 years and with more than 200 products installed.
Cryogenic Ltd's approach takes advantage of the availability of cost effective coldheads such as the Gifford-McMahon (GM) and, in recent years, the pulse tube (PT) cryocoolers to develop cryogen free applications such as DC SQUID magnetomers,
VSM systems and superconducting magnets for many types of applications. These include X-ray systems, beam-line magnets, vector magnets, ignition gyrotron magnets, bespoke magnets/cryogenics and also applications in magnetic resonance such as gyrotron magnets,
desktop superconducting magnets, dissolution DNP magnets, high field EPR magnets, Q and W-band EPR magnets, EPR cryostats, MRI magnets, wideline NMR magnets and high resolution solid state NMR magnets.
Cryogen free technologies perfectly suit superconducting magnets where the ability to sweep or switch the field is very important!
With conventional superconducting magnets, known as 'wet' magnets, such an operation is only available for restricted sweep widths and requires liquid helium dewars to be on hand to refill the magnet cryostat.
With cryogen free superconducting magnets it is possible to sweep from the negative maximum field value to the positive maximum field value without consuming any liquid helium with the minimum of
fuss and more convenience. High field EPR and wideline NMR systems were the first to be built utilising this technology. Cryogenic Limited have developed Q and W-band EPR magnets that have an
integrated variable temperature insert (VTI) using their patented approach of using a single coldhead with independent thermal circuits for the magnet and VTI. They have taken their expertise to the next level with their new high resolution solid state NMR
magnet which can be swept or made persistent at any value of its field, with a method to settle the field, making a very versatile conveniently field settable superconducting magnet.
Please continue reading for more information
concerning Cryogenic Ltd's products for Magnetic Resonance...
Cryogenic Ltd Cryogen Free Variable Temperature Cryostats for EPR
Cryogenic Ltd now make two cryogen free cryostats for use on existing EPR magnets. A new cryostat for X-band 'square' top loading cavities has been launched and is in use by a customer in the United Kingdom and joins the exisiting cryogen free cryostat for EPR (CF VTC for EPR) which has
been described as the 'Rolls Royce of cryostats! The backing image is of a high resolution rendering of the Cryogenic Ltd new cryogen free cryostat!
Cryogenic Ltd Cryogen Free Cryostat for X-band Top Loading Cavities
The new Cryogenic Ltd cryostat follows in the footsteps of the highly successful CF VTC for EPR (see below). Customers have been asking for a solution to provide the same convenience and ease of use for providing variable temperature operation for the top loading X-band cavities and this
new cryostat is the result!
The cryostat had several design requirements to achieve. These include:
a base temperature close to that of its related CF VTC for EPR product (2.8 K is achieved - actual sample temperature);
a reduced offset between the set temperature and the sample temperature (see video below showing liquid helium bubbling through the cryostat!);
the ability to run at low temperatures for extended periods of time without any requirement for liquid Helium!
The cryostat is moveable so can be moved into the magnet for use or away from the magnet when not required. The cryostat is compatible with any X-band top loading cavities that are compatible with the Oxford Instruments ESR 900 and 910 flow cryostats, including those on
Bruker and JEOL EPR spectrometers.
So, if you would like to become independent of LHe supplies, to have the convenience of being able to go to low temperatures whenever you need to or want to, including out of hours, over weekends or even holidays, please contact us!
The video below shows liquid helium bubbles in the cryostat tube from the Cryogen Free Cryostat for X-band Top Loading Cavities! Cool; literally!
Cryogenic Ltd Cryogen Free Variable Temperature Cryostat for EPR (CF VTC for EPR)
The CF VTC for EPR is Cryogenic Ltd's highly successful cryostat project for the X and Q-band EPR resonators compatible with the Oxford CF935 flow cryostats. The image below shows the various versions of the CF VTC for EPR over the last decade at (i) the MPI
for Energy Conversion, Mülheim, Germany (photo courtesy of Dr Ed Reijerse); (ii) Queen Mary & Westfield College, London, UK (photo courtesy of Dr Maxie Roessler); (iii) the University of St Andrews, Scotland (photo courtesy of Professor Graham M. Smith).
As mentioned earler, the Cryogenic Ltd CF VTC for EPR is a cryogen free replacement for the Oxford Instruments CF935 flow cryostat and has a specified temperature range of 2 to 300 K (typically a lower base
temperature of near 1.5 K can be achieved). Benefits of the CF VTC for EPR include making experimental scheduling much more efficient and convenient in addition to reduced/no cryogen costs. The key benefits are:
continuous run times over several weeks with the ability to control the temperature accurately and stabily, during which multiple samples can be conveniently measure at cryogenic temperatures
providing more efficient schedules without continuously swapping liquid helium dewars;
no dependence on liquid helium availability avoiding significant scheduling problems;
reduced complications associated with the allocation of cryogen costs between user groups for experiments allowing long term measurement schedules;
routinely achieve lower stable base temperatures (~1.7 K), allowing more systems to be investigated;
avoids Health and Safety Regulation restrictions on handling cryogens out of hours avoiding scheduling problems on weekends and liquid helium handling restrictions or when problems arise from the
blockage of transfer lines.
The plot above demonstrates the small difference between the set temperature and the actual sample temperature at below 1.4 K operation (achievable base temperatures will vary, cryostat to
cryostat) and demonstrates the temperature stability at base temperature. This measurement was made by placing a cernox sensor into an EPR tube, making the EPR glass and placing in a MD5
resonator.
The spectra to the left performed at Queen Mary College London demonstrates the convenience and ability to operate at a wide temperature range with excellent temperature stability. The figure
depicts X-band continuous wave EPR spectra of a Fe-S cluster N2 in a mitrochondrial complex undergoing an EPR-based small volume potentiometric titration.
The EPR spectra are temperature sensitive with 25 K being chosen as the desired temperature to perform the titration. The convenience allowed a resonator with a much lower sample volume to be
used requiring a much smaller amount of protein compared with previous studies.
This work has been published: see, John J. Wright, Enrico Salvadori, Hannah R. Bridges, Judy Hirst, Maxie M. Roessler, Journal of Inorganic Biochemistry
2016, 162, 201 (http://dx.doi.org/10.1016/j.jinorgbio.2016.04.025).
3He Insert for Operation at 300 mK
The CF VTC for EPR cryostat can also be used for other experiments not involving EPR such as Hall Effect measurements, etc. In these cases, it is possible to get to base temperatures down to
300 mK using the 3He insert which is fully compatible with the cryostat providing unique and additional capabilities.
The image below is indicative of the 3He insert and takes the psoition in the cryostat typically taken by a Flexline style resonator.
Please contact us if you would like to receive additional information at info@talaverascience.com.
Cryogenic Ltd Cryogen Free EPR Magnets
High-Field EPR Magnets
Cryogen free superconducting magnet systems are charged with helium gas which is then circulated using a helium compressor through a coldhead which is used to cool the magnet
superconducting winding, which is situated in a vacuum, via a thermal link. Cryogenic Ltd build magnets with permanently attached charging leads made from high Tc superconductors whose heat load is
sufficiently within the capabilities of the cryocooler. This allows simple control of the magnetic field over its entire available range and is ideal for EPR applications. The title image above is courtesy of
Professor David Britt, UCSD and is of the magnet during installation.
The cryogen free 12 T high field EPR magnet depicted to the left is
one installed at North Carolina State University and is one of the first such EPR magnets of its type. Due to the compact design of
the cryogen free superconducting magnet it has a flat top allowing it to easily interface with the dilution refrigerator (also pictured) without the usual liquid helium or liquid nitrogen towers
and this magnet has been used to probe quantum phenomena such as Luttinger-like fluids and Majorana particles. Note that PT cryocoolers, unlike GM cryocoolers, need to be mounted vertically or
close to vertical.
The image to the left is courtesy of Professor Alex Smirnov, NCSU.
Cryogenic Ltd W-band EPR Magnets with Integrated Variable Temperature Inserts
The picture above is of the cryogen free superconducting 6 T transverse field EPR magnet with integrated variable temperature insert (iVTI) and is utilised by a Bruker EPR spectrometer. The compact design
of this magnet can allow the use of X and Q-band flexline resonators making this a very versatile magnet indeed. The performance of the iVTI is that of the CF VTC for EPR mentioned earlier in this webpage.
This magnet and its iVTI makes use of Cryogenic Ltd's patented approach of having one cryocooler cooling two independent thermal circuits, one for the magnet and one for the iVTI. The magnet uses electricity
more efficiently than the conventional 2 T resistive electromagnets and uses no liquid helium for performing low temperature studies.
The photo is provided with the courtesy of Professor Dariush Hinderberger, Martin Luther Universität Halle-Wittenberg.
Cryogenic Ltd have made EPR superconducting magnets at field strengths as high as 14 T and bespoke EPR magnets such as a 5 T W-band magnet for EPR, NMR and DNP with iVTI depicted to the right was
manufactured for the Weizmann Institute of Science (photo to the right courtesy of Dr Akiva Fentuch).
Please contact us if you have any queries concerning your EPR magnet interests.
Please contact us if you would like to receive additional information at info@talaverascience.com.
Cryogenic Ltd Cryogen Free Compact and Benchtop EPR Magnets
Cryogenic Ltd have pioneered the development of very compact super
conducting magnets for use in EPR which can be used up to W-band and, in
some cases, can be placed on a bench and be moveable. As with the
other magnets provided by Cryogenic Ltd, these magnets can be provided with or without an iVTI.
The attributes of a typical benchtop cryogen free magnet are (for bespoke design specification requirements, please contact us to discuss):
Compact super conducting magnet; 440 mm x 660 mm x 900 mm (W x D x H);
Transverse or solenoidal fields;
Dry system, no cryogens required, 250 mW cryocooler;
Fully field sweepable, -B0 to +B0, the magnet power leads are permanently attached;
With or without iVTI (picture to the left shows a benchtop 3 T magnet with iVTI);
30 mm VTI access;
Variable temperature range 2 to 300 K;
Air cooled helium compressor, helium hoses (20 m) and magnet control electronics included.
Please contact us if you would like to receive additional information at info@talaverascience.com.
Cryogenic Ltd Cryogen Free NMR Magnets
Cryogenic Ltd cryogen free magnets for high resolution solid state NMR
The picture behind this section depicts a cryogen free 9.4 T/89 mm high resolution superconducting magnet situated at Cryogenic Ltd as part of an NMR instrument based on a TecMag console and
utilising a 4 mm PhoenixNMR MAS HX probe with an inverted spinning module to facilitate top loading of the sample and probe. This allows the magnet to stand on the floor and provide access to
the probe at a reasonable height (due to the compact nature of the magnet) and with convenience with the flat top. The image shows the probe inserted into the magnet and the 4 mm MAS rotor was spinning.
This magnet can be energised at different persitent B0 values up to the rated maximum for full field dependent studies. In addition, the magnet can be swept through the full static
quadrupole NMR spectrum making it simple and convenient to determine all of the relevant quadrupolar parameters, experimentally, bringing full B0 control to the NMR spectrometer.
Typically, when a superconducting magnet is energised to a new field, there is an amount of time required to allow trapped flux to escape. Left to their own devices this settling time can be on the order of
months. In a cryogen free magnet, the coil is positioned inside a vacuum and Cryogenic Ltd's magnets are around 3.8-3.9 K. In a wet magnet, the coil is typically situated in a bath of liquids helium and, unless
pumped, is at 4.2 K. Cryogenic Ltd have recently pioneered a method where the cryogen free coil can be warmed, still at a superconducting temperature, and this warming helps reduce the settling time to
the order of an hour making for very convenient changing of fields to a new persistent value. This is not possible if your coil is sitting in a reservoir of liquid helium.
This approach has been published: "On the magnetic field stability of cryogen-free magnets for magnetic resonance applications", Eugeny Kryukov, Angel Joaquin Perez
Linde, Seema Raghunathan, Stephen Burgess, Paul Jonsen, Jeremy Good, Solid State Nuclear Magnetic Resonance 105 (2020) 101639 (
https://doi.org/10.1016/j.ssnmr.2019.101639).
In the case of solid state DNP NMR, the same magnet can be used for the high-resolution NMR component AND for measuring the full EPR spectrum of the spin label allowing for the determination
of the optimal field value for the DNP NMR experiment...
The data presented below have been acquired at 7.05 T and 9.4 T demonstrating the technology's applicability for magic angle spinning (MAS) NMR (see the spectra below) and are courtesy of Dr John Hanna, U Warwick, as part
of a Knowledge Transfer Partnership (KTP) program with Cryogenic Ltd. and depict the non-integer spin quadrupolar MAS NMR spectra and 31P NMR of tricalcium phosphate at 12 kHz MAS and a plot of
magnet stability from the prototype 9.4 T solid state high resolution NMR magnet (James F. MacDonald, and John Hanna, unpublished results, 2016).
Some data acquired on a Cryogenic Ltd cryogen free magnet for high resolution solid state NMR
Cryogenic Ltd Benchtop NMR magnets
The picture to the right shows a 9.4 T compact desktop cryogen free superconducting NMR magnet, available up to 9.4 T with a 54 mm bore in either vertical (shown) or horizontal bore formats;
supplied with or without 4-channel cryoshims.
At around 50 kg, the magnet can be placed at any persistent field up to its rated maximum and be run in swept mode making this an ideal desktop magnet for field dependent studies.
In addition to the experimental benefits presented here there are others to consider:
No cryogenic experience is required;
Turn-key operation;
Overnight-cool down;
Low cost of ownership;
Minimal maintenance;
Minimal quench hazards (no loss of helium);
No liquid cryogens required, no dewars...
Bespoke designs can be discussed, such as prepolarisation NMR magnets and other applications. Please do inquire with us...
Cold Heads: Gifford-McMahon (GM) versus Pulse Tube (PT)
There are two cold head types that have use in cryogen free cryogenics and these are the Giffor-Mcmahon (GM) and the much more recently developed Pulse Tube (PT). In the applications here they both work similarly in that they are
two stage cryocoolers where the first stage, with much higher cooling power, cools to around 42 K and is typically used to cool a radiation shield in a cryogen free magnet, and the second stage which
cools to around 4 K. The cooling power of a cold head, such as 0.5 W, 1 W, etc., is that it has at around 4 K.
These cold heads have their own strengths and weaknesses and these will depend on the application they are used for. For the magentic resonace applications mentioned above on this webpage are served by the PT
cold head. However, the attributes of each of the cold heads include:
So, what are the pros and cons of each? The Gifford-Mcmahon Cold Head:
is mechanical with pistons and might generate higher vibrations than the PT cold head;
is cheaper than the PT cold head to purchase;
has a maintenance cycle of 10,000 hours of continuous use (there is a counter that decrements from 10,000 hours on the helium compressor whilst in use);
has a much stronger cooling effect and is quicker to cool equipment;
can be operated in any orientation, this means that a cooled device can be reoriented in operation.
Whereas, the Pulse Tube Cold Head:
uses a very subtle effect and there are no moving parts at the cold end, resulting in much smaller vibrations compared to the GM cold head;
is more expensive to purchase than the GM cold head;
originally had a maintenance cycle of 10,000 hours but are now typically 50,000 hours or more, making their greater acquisition cost more worthwhile
in terms of overall costs and convenience;
being subtle, has a lower cooling effect, it takes longer to cool equipment;
cannot be operated in any orientation, they are typically used in a vertical orientation.
Cryogenic Ltd recognised the adverse impacts that cold heads can have on the results of their use in magnetic resonance and have mitigated these through their design: vibrations have a detrimental effect in
all of the areas presented here on this webpage. Cryogenic Ltd continue to explore an develop methods and means to further expand the application of cryogen free technologies in magnetic resonance. Please
contact TalaveraScience if you have any questions about any magnetic resonance application and you would like to be cryogen free!
