**6. Applications**

Unique properties of HTS make them very attractive from an application point of view due to continuous enhancement in their properties (**Figure 8**). Semiconductor sciences have been consistently depriving of novel applications of superconducting materials for quite a time now. Owing to their large persistent current, ever since their discovery, SC coils have always been envisioned to be used for sturdy magnetic field production. However, a major challenge faced by Type-I (first generation) HTSs was the suppression of superconductivity by magnetic fields induced within the materials by injected current. This ceased Type-I SC's application in fields involving high current and high fields. To overcome this problem, a new class of SC materials naming Type-II (second generation) HTSs having longer magnetic penetration as compared to coherence length were fabricated. Longer penetration depths favor the presence of superconductivity even in magnetic fields presence up to a critical value (Hc2) of induced field. Another modification in HTSs was the control of power dissipation caused by Lorentz force, by properly engineered "pinning centers" that modulate the magnetic flux generated in the system [71].

#### **6.1 Transmission of commercial power**

Extremely low resistance values make HTSs an ideal candidate for transmitting commercial power to the cities. However, high cost and practically impossible implication of cryogenic temperatures to such lengthy cables limit their


**69**

*High Temperature Superconductors*

**6.2 Bio-magnetism**

*DOI: http://dx.doi.org/10.5772/intechopen.96419*

**6.3 High magnetic field in Tokamaks**

the help of Alcator devices [99].

sized devices based on B3

high power density.

application for very short distances. One example of above-mentioned application was the transmission of electricity using HTSs to 150,000 citizens of Copenhagen, Denmark back in May 2001. The transmission cable was only 30 m in length which proved to be sufficient for testing. This was the first-ever commercial power transmission using superconducting cables in history. Later, USA and Japan successfully fabricated superconducting transformers using HTSC windings. Fault currents produced can be limited by Super-Foam which is produced from YBa2Cu3Oz [13, 98].

Another important application of HTSs is in the medical field for diagnostic purposes. Non-penetrating procedures are required in the field of bio-medicine to retrieve internal information of living body. Magnetic Resonance Imaging (MRI) has been frequently used for this purpose where a strong magnetic field has impinged into the body which imposes precessional motion of H2 atoms present in the body. After removal of an external magnetic field, exciting H2 atoms release energy which is detected and graphically presented by computer. Use of SC's can enhance MRI performance owing to high magnetic field induced in them due to large current flow. Before superconductor technology, it almost took 5 hours to produce single-image initially when MRI was discovered (July 3, 1977) [71].

Developments in fusion energy department have been made after the introduction of high-temperature superconductor (HTS) based technologies that imply high magnetic field induction (>18 T) for compact experiments in fusion power plants. Operation in high magnetic fields, large current densities, higher value of cryogenic temperature, and ability to withhold extreme tensile stress make HTS a suitable candidate as compared to LTS (Low-Temperature Superconductors). A large

operating magnetic field range opens new opportunities to fabricate novel magnetic designs and improved magnetic confinement can be achieved for higher magnetic fields (> 16 T) with the help of HTS [99]. A maximum achievable induced field that depends upon current density present in HTSs has been a primary factor in fabrication of magnetic devices for fusion reactors as explained in basic tokamak design, in-depth studies, system codes, and tokamak magnet designs [100]. HTS offers a significant increase (~7.5 to 10–12 T) in on-axis BT in tokamak reactor which allows a significant increase in an applicable field in coil from 16 T to >20 T) as compared to LTS. Other advantages of HTS technology in fusion energy department include:

1.Small Burning Plasma: In mid-1980s, U.S. planted burning plasma-based fusion reactor based on the implication of SC's ability to induce large magnetic fields at a small size. The phenomenon has been successfully explained with

2.A lot of research work proposed that such small sized high field devices for burning plasma can be fabricated using copper-based magnets. Even smaller sizes can be achieved for such high field copper-based devices with the help of

3.Performance: High power density and energy gain can be attained in small-

fusion reactors. However, heat exhaust and diverter limit reduction in size and

dependence for commercial realization of such

HTS reducing their heating and structural issues as well [101].


**Figure 8.** *Schematic overview of possible applications of HTSs. Reproduced from Ref. [59].*

#### *High Temperature Superconductors DOI: http://dx.doi.org/10.5772/intechopen.96419*

application for very short distances. One example of above-mentioned application was the transmission of electricity using HTSs to 150,000 citizens of Copenhagen, Denmark back in May 2001. The transmission cable was only 30 m in length which proved to be sufficient for testing. This was the first-ever commercial power transmission using superconducting cables in history. Later, USA and Japan successfully fabricated superconducting transformers using HTSC windings. Fault currents produced can be limited by Super-Foam which is produced from YBa2Cu3Oz [13, 98].
