The fi rst wall of a magnetic fusion containment vesselhas been said to contain the most hostile environmentyet designed by man. Justify this statement.

PHYS 242 BLOCK 1, PART 1, NOTES Sections 21.1 to 21.7 Objects may have a property calledelectric charge(usually just calledcharge) (TERM 1). The SI unit of electric charge is 1 coulomb = 1 C. (Electric ) current is the motion of (electric) charge (TERM 2). The SI unit of electric current is 1 ampere = 1 amp = 1 A. Then 1 C≡ 1 A·s (≡ is the mathematical symbol for “is defined to equal”). Charge can be either positive (+) or negative (–). Particle Charge (q) Rest Mass (m 0 TERM –19 –31 electron –e = –1.602 × 10 C 9.109 × 10 kg 3 proton +e =+1.602 × 10 –19C 1.673 × 10–27 kg 4 neutron zero 1.675 × 10–27 kg 5 Neutral objects have zero total charge, which may result from equal magnitudes of positive and negative charges. We charge an object by adding or removing electrically-charged particles (SKILL 1). Charges of the same sign repel one another. Charges of opposite sign attractone another (part of SKILL 4). See Figure 21.1, page 684. The principle of conservation of charge is that the total charge in an isolated system does not change (TERM 6). The principle of quantization of charge is that the total charge of anything has only certain allowed values (TERM 7). That is,total= 0, ±e, ±2e, ±3e, … (except quarks have3± e