Thermal behavior of millimeter wavelength radio telescopes

Greve, A.; Dan, Marina; Peñalver, J.

doi:10.1109/8.202715

Cited by 21 publications

(8 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3 (Fig. 4) is obtained for a beam which consists of the diffracted beam A T and at least two persistent (Greve et al 1993(Greve et al , 1994b. When present, the transient thermal deformations are especially noticed during day time and sunshine (for instance as focus changes) and the comparison of measurements around New Moon and Full Moon illustrates this effect (see Fig.…”

Section: The Beam Parametersmentioning

confidence: 84%

“…We analyze total power scans across the Moon at 3.4 mm (88 GHz), 2.0 mm (150 GHz), 1.3 mm (230 GHz), and 0.86 mm (350 GHz) wavelength, and provide in addition to the earlier investigation of Garcia-Burillo et al (1993) the parameters of an analytic expression of the IRAM 30-m telescope beam as required for the reduction of astronomical observations, in particular of extended sources. (For a description of the 30-m telescope and its behaviour see Baars et al (1987Baars et al ( , 1994 and Greve et al (1993Greve et al ( , 1996aGreve et al ( , 1998). …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The beam pattern of the IRAM 30–m telescope

Greve

Wild

1998

Astron. Astrophys. Suppl. Ser.

Self Cite

View full text Add to dashboard Cite

Abstract. Total power scans across the Moon around New Moon (mostly day time) and Full Moon (night time) at 3.4 mm (88 GHz), 2.0 mm (150 GHz), 1.3 mm (230 GHz), and 0.86 mm (350 GHz) wavelength are used to derive the beam pattern of the IRAM 30-m telescope to a level of approximately −30 dB (0.1%) and, dependent on wavelength, to a full width of 1000 − 1400 . From the reflector surface construction and application of the antenna tolerance theory we find that the measurable beam consists of the diffracted beam, two underlying error beams which can be explained from the panel dimensions, and a beam deformation mostly due to large-scale transient residual thermal deformations of the telescope structure. In view of the multiple beam structure of the 30-m telescope, and of other telescopes with a similar reflector construction of (mini-)panels and panel frames, we summarize the antenna tolerance theory for the influence of several independent surface/wavefront deformations. This theory makes use of different correlation lengths, which in essence determine the independent error distributions, and of the wavelength-scaling of the diffracted beam and of the error beams.From the Moon scans we derive the parameters for calculation of the 30-m telescope beam in the wavelength range 3 mm to 0.8 mm as required for the reduction of astronomical observations, in particular of extended sources. The parameters of the beam are primarily for the time after July 1997 when the reflector was re-adjusted and improved to the illumination weighted surface precision of σ T = 0.065 − 0.075 mm.In the Appendix we explain the choice for this analysis of scans taken around New Moon and Full Moon.

show abstract

Section: The Beam Parametersmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

The beam pattern of the IRAM 30–m telescope

Greve

Wild

1998

Astron. Astrophys. Suppl. Ser.

Self Cite

View full text Add to dashboard Cite

show abstract

“…This is due to the fact that the fo rk arms are well-separated structures, allowing only little communication and exchange of the inside air. A com plex servo-loop-controlled climatization system may provide improvement, however, a sophisticated thermal fay ade (like an air cooled fay ade [17]) provides an easier and effective solution. Fre quent pointing (which may, however, be inconvenient) can elimi nate a large part of the thermal effects of the mount.…”

Section: Telescope Mountmentioning

confidence: 99%

“…This has been done for a long time by finite-element model (FEM) calculations of structural deforma tions under static thermal loads, such as, for instance, a thermal gradient through the telescope structure, or a random temperature distribution throughout the telescope components. However, we have emphasized earlier [17] that it is possible to be more realistic, and to simulate with good precision the time-dependent dynamic thennal behavior of a radio telescope under the influence of the time-variable environment, and to use these data in a FEM calcu lation. Here, we explain the possibility of also predicting from model calculations the thermal behavior of a servo-loop-controlled ventilatedlclimatized telescope structure with sufficient accuracy for design and operational purposes.…”

Section: Introductionmentioning

confidence: 97%

Calculated thermal behavior of ventilated high precision radio telescopes

Greve

Bremer

2006

IEEE Antennas Propag. Mag.

Self Cite

View full text Add to dashboard Cite

Radio telescopes that operate at millimeter and sub-millimeter wavelengths need a reflector-surface precision of a few tens of microns and a pointing accuracy of a few arcseconds. When built in a conventional way from steel and aluminum, as in the case of larger-diameter telescopes, thermal control must be applied to reduce temperature-induced deformations, in particular of the reflector backup structure. We illustrate that it is possible to make model calculations -for instance, during the design phase -that simulate the thermal behavior and the operation of a telescope when servo-loop-controlled ventilation or climatization (air-conditioned ventilation) of the backup structure is applied. We explain the technique of model calculations, and present as an example the calculated thermal behavior of a ventilated 64-m-diameter telescope and of the climatized 30-m IRAM telescope. It is explained that the thermal control of a telescope mount is Jess demanding if frequent pointing corrections can be made.

show abstract

“…One solution is that used on the !RAM 30-m telescope in Spain where the primary truss is insulated and a thermal control system with large fans is used to keep the truss close to the same temperature as the yoke 6 • This works well for operation at 1 mm but is unlikely to be sufficient for operation at 200 microns.…”

Section: Thermal Homologymentioning

confidence: 99%

CFRP truss for the CCAT 25m diameter submillimeter-wave telescope

2010

View full text Add to dashboard Cite

CCA T will be a 25 m diameter submillimeter-wave telescope that will operate inside a dome located on Cerro Chajnantor in the Atacama Desert. The telescope must have high aperture efficiency at a wavelength of 350 microns and good performance out to a wavelength of 200 microns. A conceptual design for a carbon fiber reinforced plastic (CFRP) truss and primary reflector support truss has been developed. This design yields a telescope with a net Y2 wave front error of < 10 microns using a lookup table to adjust the segment actuators to compensate for gravitational deflections. Minor corrections may be required to compensate for the expected 20 C temperature excursions. These can be handled using a coarse lookup table.

show abstract

Thermal behavior of millimeter wavelength radio telescopes

Cited by 21 publications

References 13 publications

The beam pattern of the IRAM 30–m telescope

The beam pattern of the IRAM 30–m telescope

Calculated thermal behavior of ventilated high precision radio telescopes

CFRP truss for the CCAT 25m diameter submillimeter-wave telescope

Contact Info

Product

Resources

About