Published online by Cambridge University Press: 17 February 2016
Let   ${\rm\Lambda}(n)$  be the von Mangoldt function,
 ${\rm\Lambda}(n)$  be the von Mangoldt function,   $x$  be real and
 $x$  be real and   $2\leqslant y\leqslant x$ . This paper improves the estimate for the exponential sum over primes in short intervals
 $2\leqslant y\leqslant x$ . This paper improves the estimate for the exponential sum over primes in short intervals  $$\begin{eqnarray}S_{k}(x,y;{\it\alpha})=\mathop{\sum }_{x<n\leqslant x+y}{\rm\Lambda}(n)e(n^{k}{\it\alpha})\end{eqnarray}$$
 $$\begin{eqnarray}S_{k}(x,y;{\it\alpha})=\mathop{\sum }_{x<n\leqslant x+y}{\rm\Lambda}(n)e(n^{k}{\it\alpha})\end{eqnarray}$$ $k\geqslant 3$  for
 $k\geqslant 3$  for   ${\it\alpha}$  in the minor arcs. When combined with the Hardy–Littlewood circle method, this enables us to investigate the Waring–Goldbach problem concerning the representation of a positive integer
 ${\it\alpha}$  in the minor arcs. When combined with the Hardy–Littlewood circle method, this enables us to investigate the Waring–Goldbach problem concerning the representation of a positive integer   $n$  as the sum of
 $n$  as the sum of   $s$
 $s$    $k$ th powers of almost equal prime numbers, and improve the results of Wei and Wooley [On sums of powers of almost equal primes. Proc. Lond. Math. Soc. (3) 111(5) (2015), 1130–1162].
 $k$ th powers of almost equal prime numbers, and improve the results of Wei and Wooley [On sums of powers of almost equal primes. Proc. Lond. Math. Soc. (3) 111(5) (2015), 1130–1162].